The pre-dawn attacks on Saturday knocked out more than half of crude output from the world's top exporter - five percent of the global oil supply - and cut output by 5.7 million barrels per day.
Yemen's Houthi rebels, who have been locked in a war with a Saudi-UAE-led coalition since 2015, claimed responsibility for the attacks, warning Saudi Arabia their targets "will keep expanding".
But US Secretary of State Mike Pompeo swiftly accused Iran of being behind the assault, without providing any evidence. The claim was rejected by Tehran that said the allegations were meant to justify "actions" against it.
Saudi Arabia, meanwhile, promised to "confront and deal with this terrorist aggression", while US President Donald Trump hinted at possible military action.
Here are the latest updates:
Thursday, September 19
Russia calls for talks to defuse tensions
Russian Foreign Minister Sergei Lavrov on Thursday urged all countries in the Gulf to sit down for talks to defuse tensions following an attack on Saudi oil infrastructure, Russian news agency Interfax reported.
Speaking in Moscow, Lavrov called for measures to be put in place to stop a similar situation happening in the region again and said that groundless accusations against Iran over the attacks were inflaming tensions.
Iran's foreign minister Javad Zarif warns of 'all-out war'
Iranian Foreign Minister Mohammad Javad Zarif said that the result of any US or Saudi military strike against his country would result in an "all-out war".
"I am making a very serious statement that we don't want war; we don't want to engage in a military confrontation ... But we won't blink to defend our territory," Zarif told CNN.
Yemen rebel claim over Saudi oil attacks 'lacks credibility': France
French Foreign Minister Jean-Yves Le Drian said that a claim by Yemeni rebels to have carried out attacks on two Saudi oil facilities "lacks credibility".
"The Houthis, who are Yemeni rebels, announced that it was they who provoked this attack, which lacks credibility," Le Drian told France's CNews channel referring to the missile and drone strikes, which the US and Riyadh have blamed on Saudi's arch-foe Iran.
"But given that there is an international investigation let's wait for the results," he added.
Le Drian linked the timing of the strikes to next week's UN General Assembly in New York, where a meeting President Donald Trump and his Iranian counterpart Hassan Rouhani had been mooted.
"We need now to return to the principle of de-escalation," he said.
Saudi envoy to Germany says all options on the table against Iran
Prince Faisal bin Farhan Al Saud said Iran is 'certainly' behind Saudi oil plant attacks [File: Alexander Becher/ EPA]
The Saudi ambassador to Germany said all options were on the table in retaliation to attacks on Saudi Arabia's oil facilities that the kingdom has blamed on Iran.
Asked about the possibility of a military strike against Iran, Prince Faisal bin Farhan Al Saud said: "Of course everything is on the table but you have to discuss that well".
"We're still working on where they were launched from but wherever they came from, Iran is certainly behind them as Iran built them and they could only be launched with Iranian help," he told Germany's Deutschlandfunk radio.
UAE joins US-led coalition to protect Middle East waterways
The United Arab Emirates says it has joined a US-led coalition to protect waterways across the Middle East after an attack on Saudi oil installations.
The state-run WAM news agency quoted Salem al-Zaabi of the Emirati Foreign Ministry as saying the UAE joined the coalition to "ensure global energy security and the continued flow of energy supplies to the global economy."
Saudi Arabia joined the coalition on Wednesday. Australia, Bahrain and the United Kingdom also are taking part.
The US formed the coalition after attacks on oil tankers that US officials blame on Iran, as well as Iran's seizure of tankers in the region. Iran denies being behind the tanker explosions.
Wednesday, September 18
Kuwait army prepares as regional tensions soar
Kuwait's army said it was raising its readiness levels and carrying out military exercises amid soaring regional tensions.
Kuwait also said it was investigating accounts that a drone intruded into its airspace and flew over the royal palace on Saturday, the same day two Saudi oil facilities were attacked.
The army was aiming to reach the "highest levels of readiness and combat efficiency" in order to "preserve the security of the country and the safety of its lands, waters and airspace from any potential dangers".
Kuwait's government has already beefed up security measures around vital installations in the country.
Kuwait's Al-Rai newspaper reported at dawn on Saturday, an unmanned drone about the size of a small car came down to a height of about 250 metres over the palace, before turning on its lights and flying away.
It said the drone continued flew over the seaside residential palace of Emir Sheikh Sabah al-Ahmad Al-Sabah, who is undertaking medical tests in the United States.
Pompeo: Saudi oil attacks an 'act of war'
US Secretary of State Mike Pompeo denounced attacks on Saudi Arabia's oil infrastructure as an "act of war", as he arrived in the kingdom.
"This was an Iranian attack," Pompeo told reporters on his plane before landing in the western city of Jeddah, calling it "an act of war".
Pompeo met Crown Prince Mohammad bin Salman (MBS) and is scheduled to travel to neighbouring United Arab Emirates next.
Pompeo takes part in a meeting with MBS in Jeddah [Mandel Ngan/Reuters]
Saudi Arabia 'knows nothing', says Iranian official
Saudi Arabia proved that "it knows nothing", an adviser to Iran's President Hassan Rouhani said, after the kingdom displayed evidence it said proved the assault on its oil sites was "unquestionably sponsored" by Tehran.
"The press conference proved that Saudi Arabia knows nothing about where the missiles and drones were made or launched from and failed to explain why the country's defence system failed to intercept them," Hesameddin Ashena wrote on Twitter.
Yemen's Houthis threaten to attack UAE targets
Yemen's Houthi rebels threatened to attack the UAE, days after they claimed attacks on key oil facilities in Saudi Arabia.
Yahia Sarie, a spokesperson for the Houthi forces, told a press conference they have "dozens of targets" in the UAE that "could be targeted at any time."
He also added the Houthis have new drones, powered by "normal and jet engines" that can reach targets deep in Saudi Arabia.
Saudi: Oil attacks unquestionably sponsored by Iran
Saudi Arabia's defence ministry said the weekend attacks on the kingdom's oil facilities came from the north and were "unquestionably sponsored by Iran".
At a press conference in the capital, Riyadh, to reveal the military's findings, Saudi defence ministry spokesperson Col. Turki al-Malki said Iranian cruise missiles and drones were used.
"The attack was systematically and intentionally planned to destroy civilian infrastructure," he said.
The US mission to the UAE said Secretary of State Mike Pompeo will meet Saudi Arabia's Crown Prince Mohammed bin Salman in Jeddah to discuss the attack and coordinate efforts against "Iranian aggression".
Pompeo will then travel to the UAE capital Abu Dhabi to meet with its crown prince, Sheikh Mohammed bin Zayed, and discuss regional and bilateral issues, it added.
Zarif rejects US accusations as 'distraction'
Iran dismissed US accusations over weekend attacks of Saudi Arabia's oil sites as a distraction from the realities in the Middle East, the Iranian Students' News Agency (ISNA) quoted Foreign Minister Mohammad Javad Zarif as saying on Wednesday.
"The United States should seek to look at the realities in the region, rather than simply using distractions. We feel that the US government is trying to somehow forget the realities in the region," Zarif said.
Zarif said the US was trying to forget realities in the Middle East [File: Evgenia Novozhenina/ Reuters]
Iran to US: Response to any attack 'won't be limited to its source'
Tehran's retaliation to any military attack will not be "limited to its source", Tehran said, in an official note to Washington, according to Iran's semi-official ISNA news agency.
"In an official note to the United States via Swiss embassy, Iran has reiterated that it was not behind attacks on Saudi Arabia's oil facilities and it has warned that any move by America against Iran will get immediate reaction," ISNA reported.
MBS: Attack on Saudi a 'real test of global will'
Mohammed bin Salman, Saudi Arabia's crown prince, said the weekend attack posed a "real test of the global will" to confront subversive acts that threaten international stability, state media reported.
His comments were made in a telephone conversation with South Korean President Moon Jae-in, who called on the global community to "take a firm stand and resolute action" towards such assaults, according to the Saudi Press Agency.
Ahead of UNGA, US 'yet to issue visas' for Rouhani, Zarif
Saudi oil attacks: UN Security Council holds back on blaming Iran
Iranian President Hassan Rouhani and Foreign Minister Mohammad Javad Zarif may not go to the United Nations General Assembly next week as the US has yet to issue them visas, according to state media.
IRNA's report said Iran's first delegation for the annual event in New York had not left the country due to not having visas.
It said Zarif was to travel there on Friday, with Rouhani following behind on Monday.
The report came as the UN meeting had been floated as the possible site of a direct meeting between US President Donald Trump and Rouhani.
US citizens warned over travelling to Saudi
The US State Department issued a travel advisory calling on US citizens to "exercise increased caution" while travelling to Saudi Arabia.
The note posted on the State Department's website said US Mission personnel and their families were not permitted to use Abha airport without approval.
The airport has been frequently attacked by drones and missiles launched by Yemen's Houthi rebels.
Defence minister denies Iran played any role in attack
Iran's defence minister Brigadier General Amir Hatami said Tehran had no involvement in the attacks on the Aramco oil installations, according to the semi-official Tasnim news agency.
"Rejecting comments about Iran's role in the operation, [Hatami] said the issue is very clear: There has been a conflict between two countries [Yemen and Saudi Arabia]." Tasnim said.
Saudi oil attacks: Iran denies links to drone strikes
Saudi promises 'material evidence' linking Iran to attack
The Saudi defence ministry said it will hold a news conference at 14:30 GMT to present "material evidence and Iranian weapons proving the Iranian regime's involvement in the terrorist attack".
Riyadh previously said preliminary results showed the attack did not come from Yemen.
Rouhani: Houthi attacks 'warning' to end Yemen war
Iranian President Hassan Rouhani told a cabinet meeting that the Houthis attacked the Saudi oil facilities as a "warning" for Riyadh to end its long-running war in Yemen.
In a video released by state TV, Rouhani did not address US and Saudi allegations that Iran was behind the drone assaults, but blamed the two countries for the conflict in the Arab world's most impoverished country.
"We don't want conflict in the region ... Who started the conflict? Not the Yemenis. It was Saudi Arabia, the Emirates, America, certain European countries and the Zionist regime [Israel] which started the war in this region," Rouhani said in the video.
Japan not aware of any Iranian involvement
Japan's new defence minister said his country has not seen any intelligence showing Iranian involvement in the attacks on the Saudi oil facilities.
"We are not aware of any information that points to Iran," Defence Minister Taro Kono told reporters at a briefing. "We believe the Houthis carried out the attack based on the statement claiming responsibility."
Japan has maintained cordial ties with Iran even as relations between Tehran and Washington have deteriorated. Kono earlier said Japan cannot participate in any military retaliation because of constitutional restraints and would instead pursue a diplomatic solution to the current crisis.
France to send experts to probe attacks
President Emmanuel Macron said France, in response to a Saudi request, will send experts to probe the drone attacks on the Saudi Aramco facilities
In a statement, the Elysee Palace said the president strongly condemned the attack and assured Crown Prince Mohammed bin Salman that France was committed to stability in the Middle East.
"In response to a Saudi request, President Macron confirmed to the crown prince that France will send experts to Saudi Arabia to take part in investigations aimed at revealing the origin and modalities of the attacks," it added.
The US formed the coalition after attacks on oil tankers [Mass Communication Specialist 2nd Class M. J. Lieberknecht/ US Navy via AP]
Saudi Arabia to join US-led maritime coalition
Saudi Arabia said it would join a US-led coalition to secure the Middle East's waterways after the attack on its oil fields.
The state-run Saudi Press Agency carried a statement quoting an unnamed official saying that the kingdom had joined the International Maritime Security Construct, a mission already joined by Australia, Bahrain and the United Kingdom.
Washington formed the coalition after attacks on oil tankers that US officials blame on Iran over Iranian denials, as well as Tehran's seizure of tankers operating in the region.
Oil prices drop as Riyadh says production will be restored
Oil prices extended their losses, after Saudi Arabia's energy minister said the kingdom will restore lost oil production by the end of the month.
But investors remained cautious about potential tension in the Middle East following the attacks.
Brent crude oil futures fell 36 cents, or 0.6 percent, to $64.19 a barrel by 00:05 GMT, after tumbling 6.5 percent the previous session.
US West Texas Intermediate (WTI) crude futures fell 43 cents, or 0.7 percent, to $58.91 a barrel, after sinking by 5.7 percent on Tuesday.
Tuesday, September 17
Pence says 'US is prepared, locked and loaded'
United States Vice President Mike Pence on Tuesday commented on Saturday's attacks on Saudi Arabian oil facilities by saying the US is "ready to defend our interests & allies in the region".
"In the wake of this weekend’s unprovoked attack on several oil facilities in Saudi Arabia, I promise you: We’re ready. The US is prepared, we’re locked and loaded," Pence said on Twitter following a talk at the Heritage foundation.
Pence also spoke to Chuck Schumer, according to the Democratic Senator and Senate minority leader.
Pence told Schumer that Secretary of State Pompeo is going to Saudi Arabia and senators will receive a classified briefingtomorroworThursday on the situation.
"Any kind of significant action should get the ok of Congress," Schumer said. "My worry here is that they will bumble into war, even if they don’t want one. They will bumble into it because they haven’t had a strategy."
Saudi Arabia: Supply levels back to levels from before attack
The Saudi Arabian Energy minister Prince Abdulaziz bin Salman said on Tuesday evening the country's oil supply levels are back at the levels they were at before the Saturday attack on some of its production facilities.
He added that the country's oil market will be fully back online at the end of September.
Bin Salman also called on the international community to "take strong action against the attack on the global economy and energy markets", both he also said he "did not know" who was behind the attack, AFP news agency said.
Iran's Zarif: US 'in denial' over Saudi attack
Iran's foreign minister said in a tweet the United States was in denial for suspecting Iran over attacks on Saudi oil facilities, and ignoring that Yemenis were fighting back after years of war against the kingdom.
"US is in denial if it thinks that Yemeni victims of 4.5 yrs of the worst war crimes wouldn't do all to strike back.
"Perhaps it's embarrassed that $100s of blns of its arms didn't intercept Yemeni fire," Mohammad Javad Zarif said. "But blaming Iran won't change that."
UK, Germany urge 'collective response' to Saudi attacks
Britain and Germanyon Tuesdayurged the international community to forge a "collective response" to the drone attacks on Saudi Arabia's oil installations, which US officials have blamed on Iran.
British Prime Minister Boris Johnson and German Chancellor Angela Merkel discussed the attacks during a telephone call, agreeing on "the need to work together, alongside international partners, to agree a collective response," according to Downing Street.
Johnson and Merkel stressed the "importance of avoiding the further escalation of tensions in the region".
Saudi clerics ordered to 'bless security' after attacks
Saudi Arabia instructed clerics across the country to focus their upcoming Friday sermons on the recent attacks that struck key oil installations in the kingdom's east.
The Islamic Affairs Ministry said the sermons should "emphasise the blessing of security and stability that God has bestowed upon the kingdom of Saudi Arabia", and the "need to rally around its wise leadership", as well as to ask for God's protection of the country and to respond to enemies where they are.
The ministry said its efforts are aimed at raising awareness about the dangers facing Saudi Arabia and the importance of supporting its rulers.
The ministry's instructions were published by the state-run Saudi Press Agency.
Pompeo headed to Saudi Arabia
US Secretary of State Mike Pompeo will travel to Saudi Arabia on Tuesday amid increased tensions in the Gulf region following the attacks on the Saudi oil installations.
"The secretary of state is traveling to Saudi Arabia today to discuss our response," Pence said during a speech at the Heritage Foundation.
However, France said it had not seen any proof that would lead it to conclude the attack was launched by or from Iran.
French FM: 'No proof to say where drones came from'
French Foreign Minister Jean-Yves Le Drian told reporters in Cairo on Tuesday his country had seen no evidence yet proving the country of origin of the drones that attacked Saudi oil installations on Saturday.
"Up to now, France does not have any proof that would allow us to say where the drones came from," Le Drian said.
Le Drian added in a news conference alongside his Egyptian counterpart "there must be a strategy of de-escalation" and supported Saudi proposals to involve the United Nations in the investigation.
US officials claim attack came from Iran: reports
USofficials said the attack on the oil installations came from Iran, both AFP and Reuters news agencies.
According to the officials, who did not want to be named, the exact location from where the attack was launched was identified to be somewhere in southwest Iran, adding that both cruise missiles and drones were used in the attack.
The official said the US was gathering evidence about the attack to present to the international community, notably European allies, at the UN General Assembly next week.
Saudi Aramco to meet oil commitment to Asian refiners: report
This is the first indication that its supply to top consumers in Asia - who consume more than 70 percent of total Saudi crude oil - will remain stable.
However, at least one refiner has been told of a partial change in the grade of crude it will receive.
Three state-owned refineries in India - Indian Oil Corp (IOC), Bharat Petroleum Corp Ltd (BPCL) and Mangalore Refinery and Petrochemicals Ltd will receive full allocated volumes of Saudi crude oil in October, three industry sources told the Reuters news agency.
But Aramco has informed India's top refiner, IOC, that it would give some volumes of Arabian Heavy instead of Arabian mix oil, said one of the sources, who declined to be identified as he was not authorised to speak to media.
Two refiners, in China and Taiwan, also said Saudi Aramco had told them that there was no change to the loading schedule in September and October.
The attack on Saudi oil facilities will not affect Aramco's public listing plans, the world's biggest oil company said.
Despite the fact it could take months for Aramco to restore its output after Saturday's attacks, the company is continuing to prepare for a local initial public offering (IPO), which the sources said may happen as early as November.
The state-owned oil group will meet local Saudi banks to discuss the IPO plans, but bankers at international lenders working on the IPO told Reuters there had been no communication from Aramco's management on any delay.
The Aramco IPO is a pillar of an ambitious economic diversification drive by Crown Prince Mohammed bin Salman (MBS), who has put the firm's valuation at $2 trillion. The domestic flotation is the first step of a targeted five percent sale.
Saudi Arabia, the world's top crude exporter, recently accelerated plans for the IPO, naming a new chairman for Aramco and mandating nine banks in top roles.
Kuwait calls on armed forces to be on high alert
Kuwait's Foreign Minister Sheikh Sabah al-Khalid Al Sabah called on the country's armed forces to be on high alert following the recent increase in tensions in the Gulf region, state news agency KUNA reported.
He also said the armed forces should be prepared to confront any incident that may destabilize the country’s security.
Kuwait stands behind Saudi Arabia following Saturday’s attacks on Aramco oil facilities, the foreign minister added.
Saudi king says Riyadh is capable of responding to attacks
Saudi King Salman said that Riyadh was capable of dealing with the consequences of attacks on its installations.
A statement issued after a meeting of Saudi Arabia's council of ministers said the cabinet had reviewed the damage caused by the attacks on the Aramco installations, and it called on the world's governments to confront them "regardless of their origin".
In the statement, the council said the "cowardly" strikes on its oil facilities were an extension of "repeated attacks" on vital installations. "[The attack] has threatened freedom of shipping, and has affected the stability of the global economic growth," the statement said, as reported by state media.
Merkel urges return to Iran nuclear deal to defuse tensions
German Chancellor Angela Merkel has called for a return to the 2015 international deal curbing Iran's nuclear activities as the only way to defuse tensions in the Middle East.
"We believe that the deal to stop Iran from acquiring military nuclear capabilities is a building block we need to get back to," Merkel said, during a news conference with Jordan's King Abdullah.
"But there is also a long list of other burdens coming from Iran like the ballistic missiles programme and its engagement in Syria," she said. "In recent days tensions in the region rose and Germany will always be in favour of de-escalation and long-term solutions are only possible through a political process."
German Chancellor Angela Merkel spoke at a joint news conference with Jordan's King Abdullah in Berlin [Fabrizio Bensch/Reuters]
NATO following aftermath of Saudi oil attacks 'with concern'
NATO is keeping a close eye on developments in the wake of Saturday's drone attacks, its head said.
"Any disruption to global energy supplies is clearly of concern to NATO Allies. We are monitoring developments carefully and with concern," Secretary-General Jens Stoltenberg told Anadolu Agency.
Stoltenberg urged all parties to prevent further such incidents, which he said pose a "serious threat" to regional security.
Trump says he would 'certainly like to avoid' war with Iran (2:18)
Aramco oil deliveries to China 'will be delayed'
Saudi Aramco informed PetroChina that some of its loadings of light crude oil for next month will be delayed by up to 10 days, according to a senior Chinese state oil source with knowledge of the matter.
However, Saudi Arabia's state oil company will still supply the same grades and volumes of light crude oil requested for October nominations, the source told Reuters news agency.
The Chinese state refiner was also told that some of its September-loading light crude cargoes will be swapped to heavier grades with no change in volumes or delays, the source said.
"The (loading dates and volumes of) September cargoes are too prompt to be changed, as Aramco may be still assessing the damages to its facilities."
Russia: No request to mediate between Saudi and Iran
The Kremlin said it had not received a formal request from any party for Moscow to act as a mediator between Saudi Arabia and Iran following the attack on Saudi Arabia's oil infrastructure.
Speaking to reporters on a conference call, Kremlin spokesman Dmitry Peskov said Moscow had not received any new information about the attack that could help it draw any final conclusions.
"We do not favour any kind of hurried accusations or conclusions about who is responsible for this attack," Peskov said.
Iran leader rules out negotiations with the US
Iran will not hold talks with the United States and Washington's policy of maximum pressure on Tehran will fail, the country's Supreme Leader Ali Hosseini Khamenei said.
"The policy of 'maximum pressure' against Iran is worthless," state TV quoted Khamenei as saying.
1. Negotiation with U.S. means imposition of their demands on Iran 2. Negotiation means a show of the success of U.S.’s policy of maximum pressure. That’s why the respected President, FM & others unanimously declared we won’t negotiate with U.S. bilaterally or multilaterally.
"All Iranian officials unanimously believe there will be no negotiations with the US at any level," he said.
Khamenei added that if Washington changes its behaviour and returns to Iran's 2015 nuclear deal, "then it can join multilateral talks between Iran and other parties to the deal".
Iranian Supreme Leader Ali Hosseini Khamenei says his country will not engage in talks with the US [File: EPA]
Japan's Abe to meet Rouhani at UNGA
Japanese Prime Minister Shinzo Abe said on Tuesday he would meet with Iranian President Hassan Rouhani at the end of the month, public broadcaster NHK said.
During a meeting with members of the ruling Liberal Democratic Party, Abe repeated his intention of speaking with Rouhani on the sidelines of the United Nations General Assembly (UNGA) in New York, according to the NHK.
Abe added that he would travel to Belgium after the UNGA session and meet with European Commission President Jean-Claude Juncker, the NHK added.
Saudi Arabia invites global experts to investigate attack
Riyadh said its initial investigations indicated that Iranian weapons were used in the attacks on its key oil installations and said it would "invite United Nations and international experts to view the situation on the ground and to participate in the investigations".
"The kingdom will take the appropriate measures based on the results of the investigation, to ensure its security and stability," a statement from the Saudi Ministry of Foreign Affairs said.
Saudi Arabia "affirms that it has the capability and resolve to defend its land and people, and to forcefully respond to these aggressions," the statement added, calling the attack "an unprecedented act of aggression and sabotage" and an "egregious crime which threatens international peace and security".
Price of oil jumps nearly 15 percent
Oil prices ended nearly 15 percent higher on Monday, with Brent crude logging its biggest jump in more than 30 years amid record trading volumes.
Brent crude futures settled at $69.02 a barrel, rising $8.80, or 14.6 percent - its largest one-day percentage gain since at least 1988.
In the US, West Texas Intermediate futures ended at $62.90 a barrel, soaring $8.05, or 14.7 percent - the biggest one-day percentage gain since December 2008.
Monday, September 16
Trump says 'looks like' Iran responsible for Saudi attacks
Trump said it's "looking like" Iran was responsible for the attacks on key oil installations in Saudi Arabia, but he said he did not want war.
Trump said at the White House that the US was not looking at retaliatory options until he had "definitive proof" that Iran was responsible.
Still, Trump told reporters in the Oval Office that the US "is prepared" if the attacks warranted a response.
Putin proposes Russian missile defence for Saudi Arabia
Russia is ready to help Saudi Arabia following attacks on the Saudi oil industry if needed, Russian President Vladimir Putin said, after talks with the leaders of Turkey and Iran in Ankara. Putin also proposed Russian weapons for purchase.
"We are ready to provide respective assistance to Saudi Arabia, and it would be enough for the political leadership of Saudi Arabia to make a wise government decision - as the leaders of Iran did in their time by purchasing S-300 and as [Turkish] President [Recep Tayyip] Erdogan did by purchasing the latest S-400 Triumph air defence systems from Russia," Putin said.
These Russian weapons would protect any infrastructure facilities in Saudi Arabia, he added.
Attack on Saudi 'unprecedented', says Pentagon chief
US Secretary of Defense Mark Esper said the recent attack on Saudi Arabian oil facilities was "unprecedented" and the US, along with its allies, was working to defend the "international rules-based order that is being undermined by Iran".
The United States military, with our interagency team, is working with our partners to address this unprecedented attack and defend the international rules-based order that is being undermined by Iran.
In a series of Tweets, Esper said he spoke with Saudi Arabia's Crown Prince Mohammed bin Salman (MBS) and the Iraqi Minister of Defence Najah al-Shammari, over the weekend
Rouhani: Saudi attacks a reciprocal response by Yemen
An attack on Saudi Arabia's Aramco oil facilities was a reciprocal measure by "Yemeni people" to assaults on their country, said Iranian President Rouhani, hours after a Saudi-led coalition said the attacks were carried out with Iranian weapons.
"Yemeni people are exercising their legitimate right of defence ... the attacks were a reciprocal response to aggression against Yemen for years," Rouhani told a joint news conference with his Russian and Turkish counterparts.
Will the attacks on Saudi oil facilities cripple global supplies?
Saudi Arabia has tried to reassure the world that it will quickly recover from Saturday's attacks on its oil plants.
However, the reassurance failed to stop oil prices soaring 19 percent - their highest-ever increase in a day.
Will the attack force us to rethink our reliance on oil?
India has condemned the attack on key Saudi oil installations over the weekend as an "act of terrorism".
Raveesh Kumar, India's foreign ministry spokesman, expressed India's resolve to "oppose terrorism in all its forms and manifestations" in a short statement.
Saudi Arabia is India's second-largest oil supplier after Iraq.
Israel 'prepared' for spillover from Saudi oil attacks
Israel is prepared for the possibility it might be drawn into any US-Iranian confrontation over the attacks on two Saudi oil plants, Prime Minister Benjamin Netanyahu said.
"I am taking care of our security on a 360-degree basis, and I can tell you that we are well prepared," Netanyahu told Army Radio when asked whether Iran might try to provoke Israel.
Analysis: Saudi attacks a 'game-changer' in US-Iran ties
The attacks on Saudi oil facilities are a "game-changer" in US-Iran relations, according to Al Jazeera's senior political analyst Marwan Bishara.
"The US cannot allow this incident to set a precedent, where more incidents like this happen in the future," he said from London.
"As far as the US is concerned, the responsibility lies with Tehran, and they are going to have to do something - whether its war or serious diplomacy - it remains to be seen."
Oman calls Saudi oil attack 'pointless escalation'
Oman expressed regret for the weekend attack on Saudi Aramco's oil facilities, with a tweet by the foreign ministry calling it a "pointless escalation".
The sultanate urged the UN special envoy to Yemen to bring together for peace talks the warring parties in the Yemen conflict, and expressed Oman's readiness to help achieve peace.
Saudi-led coalition: Iranian arms used in oil attacks
The Saudi-led military coalition battling Yemen's Houthi movement said the attack on Saudi Arabian oil plants was carried out with Iranian weapons and was not launched from Yemen, according to preliminary findings.
Coalition spokesman Colonel Turki al-Malki said that an investigation into Saturday's attacks was still ongoing to determine the launch location.
"The preliminary results show that the weapons are Iranian and we are currently working to determine the location ... The terrorist attack did not originate from Yemen as the Houthi militia claimed," Malki told a news conference in Riyadh.
UN envoy: 'Not clear' who is behind Saudi oil attack
UN special envoy to Yemen told the UN Security Council it was "not entirely clear" who was behind Saturday's attack on Saudi oil facilities, but he said it had increased the chances of a regional conflict.
"It's not entirely clear who was behind the attack, but the fact that Ansar Allah has claimed responsibility is bad enough," Martin Griffiths told the council, using the official name of Yemen's Houthi group.
"This extremely serious incident makes the chances of a regional conflict that much higher," he said.
"With Yemen in some way or other linked, none of that is good for Yemen. And this is frankly terrifying."
Remember when Iran shot down a drone, saying knowingly that it was in their “airspace” when, in fact, it was nowhere close. They stuck strongly to that story knowing that it was a very big lie. Now they say that they had nothing to do with the attack on Saudi Arabia. We’ll see?
Saudi Arabian officials are considering delaying plans to sell shares in Saudi Aramco to the public following Saturday's drone attacks on the state oil giant's facilities, the Wall Street Journal reported, citing people familiar with the matter.
Saudi energy officials and Aramco executives are discussing whether to reschedule its initial public offering (IPO) until after production is fully restored to normal levels, according to the WSJ.
Saudi Arabia shut down its crude oil pipeline to Bahrain after attacks on Saudi oil facilities, two trade sources told Reuters news agency.
The pipeline, which carries 220,000 to 230,000 barrels per day (bpd) of Arab Light crude from state oil company Saudi Aramco to Bahrain's Bapco, was closed after Saturday's attack reduced output of mainly light crude grades, one of the sources said.
Bapco is working to secure vessels to bring in about two million barrels of Saudi crude as a result of the pipeline shutdown, the sources said.
US 'weighs more intel sharing' with Saudi Arabia
The US is considering increasing its intelligence sharing with Saudi Arabia after Saturday's attack on Saudi oil facilities that halved the kingdom's production and jolted world oil markets, US officials told Reuters news agency.
The officials, who spoke on condition of anonymity, did not say how broad any increase in intelligence sharing might be.
But the US, long wary of deep involvement in the war in Yemen, has only selectively shared intelligence with Riyadh about the threats from Yemen's Iran-aligned Houthi rebels.
US, Iran trade barbs at UN nuclear watchdog meeting
The US and Iran traded barbs over Tehran's nuclear activities as the International Atomic Energy Agency's general conference got under way in Vienna
Reading a note from Trump, Energy Secretary Rick Perry said Washington "will continue to apply maximum pressure both diplomatically and economically to deny Iran any pathway to a nuclear weapon."
The US last year pulled out unilaterally from the 2015 deal with Iran that promised it economic incentives in exchange for curbs on its atomic activities and has instituted new sanctions that have been hurting the Iranian economy.
Ali Akbar Salehi, head of Iran's nuclear programme, slammed the move, saying "the destructive behaviour of the US administration and the economic terrorism pursued by it against other countries should be condemned and rejected."
Russia: Don't blame Iran for Saudi attacks
Russia's foreign ministry expressed "grave concern" about a weekend attack on key oil facilities in Saudi Arabia.
The ministry said in a statement that it condemns attacks on vital infrastructure or any actions that could disrupt global energy supplies and upset energy prices.
Moscow, however, warned other countries against blaming Iran for the attack and said that plans of military retaliation against Iran were unacceptable.
US believes drone attack not launched from Iraq: Baghdad
Iraq said it had been told by the US that Washington did not suspect the weekend attack on Saudi Arabia had been launched from Iraqi territory.
US Secretary of State Mike Pompeo had told Iraq's Prime Minister Adel Abdul Mahdi by phone "the information they have confirms the Iraqi government's statement that its territory was not used to carry out this attack," the Iraqi government said.
The Iraqi statement said Pompeo and Abdul Mahdi had agreed to share intelligence over the attack.
"The prime minister stressed that Iraq's duty was to safeguard its own security and stability, to avoid any escalation, and to prevent its territory being used against any neighbouring, brotherly or friendly country," his office said.
Trump-Rouhani UNGA meeting not on our agenda, Iran says
A meeting between the presidents of Iran and the US on the sidelines of an upcoming United Nations General Assembly (UNGA) is not on Tehran's agenda, the Iranian Ministry of Foreign Affairs has said.
"We have neither planned for this meeting, nor do I think such a thing would happen in New York," spokesman Abbas Mousavi told state television.
Media reports speculated that a drone travelling south from Iraq to the eastern oilfields of Saudi Arabia could have travelled over the sea or through Kuwait's airspace.
Kuwait's Al Rai newspaper said at dawn on Saturday, an unmanned drone about the size of a small car descended to a height of about 250 metres (820 feet) over the palace, before turning on its lights and flying away.
"Security officials have started the necessary investigation regarding the drone that was seen flying over the coastal area of Kuwait City," it said.
China, Russia call for de-escalation of tensions
China's foreign ministry said it was "irresponsible" to blame anyone for the weekend attack on Saudi Arabia, given the absence of a conclusive investigation.
Chinese Ministry of Foreign Affairs spokeswoman Hua Chunying said Beijing was opposed to the intensification of any conflict.
"We call on the parties concerned to avoid actions that could escalate regional tensions," Hua said.
In a similar fashion, the Kremlin warned against a hasty reaction to the drone attacks.
"We call on all countries to avoid hasty steps or conclusions that could exacerbate the situation, and on the contrary keep to a line of conduct that will help soften the impact of the situation," Kremlin spokesman Dmitry Peskov told journalists.
Iran says Rouhani-Trump meeting unlikely
Iran's government said it will not negotiate with the US while it is under its sanctions and urged Washington to return to the 2015 nuclear deal between Tehran and world powers.
Iranian Government spokesman Ali Rabiei said on Monday that lifting the sanctions was a main pre-requisite to resuming negotiations. Rabiei said that halting all penalties was the "necessary condition for starting constructive diplomacy".
Last year, Trump pulled the US out of the deal between Iran and world powers and reimposed sanctions on the Islamic republic that sent the country's economy into freefall.
German FM: Saudi oil plant attack very 'worrisome'
Germany's foreign minister sharply condemned the attack on the oil sites in Saudi Arabia.
Heiko Maas told reporters on Monday in Berlin the situation was "exceedingly worrisome", adding "this is really the very last thing that we currently need in this conflict."
Maas said while Germany was aware of Houthis' claim of responsibility, it was currently evaluating with its partners who was behind the attack.
According to the country's Petroleum Industry Association, only 1.1 percent of German oil imports were from Saudi Arabia.
EU urges 'maximum restraint' over attacks on Saudi oil facilities
The European Union stressed its call for "maximum restraint" following the weekend attacks on the Saudi oil facilities.
EU spokeswoman Maja Kocijancic told journalists: "We see them [the attacks] as a real threat to regional security, and at a time that tensions in the region are running very high this attack undermines ongoing work at de-escalation and dialogue."