OPEC+ energy ministers meeting in emergency session in Vienna agreed Tuesday to add roughly 1.5 million barrels a day of crude oil to global supply over the next six weeks, the alliance’s largest coordinated production response since the pandemic and an unmistakable signal that the war between Iran and a U.S.-Israeli coalition has begun to fracture the producer group’s long-standing discipline.

The decision, announced in a joint communique read shortly before 10 p.m. local time by Secretary-General Haitham al-Ghais, sent Brent crude tumbling nearly 9 percent in after-hours electronic trading. The benchmark contract, which had closed near $123 a barrel Monday and touched an intraday peak of $125.80 last week, slid through $113 within minutes of the announcement and continued lower into the Asian session. Analysts said the move would likely pull Brent toward $108 over the coming days if the alliance followed through on the agreed barrels.

Saudi Arabia and the United Arab Emirates will together supply the bulk of the increase, accounting for roughly 1.1 million barrels per day of the headline figure, according to the communique. Kuwait, Iraq and Algeria committed smaller volumes. Russia, which had publicly resisted any significant production response in the run-up to the meeting, agreed to a notional 150,000-barrel-a-day contribution that delegates said was largely face-saving and unlikely to translate into materially higher Russian exports given existing pipeline and tanker constraints.

“This decision is an act of stewardship, not of politics,” Saudi Energy Minister Prince Abdulaziz bin Salman said at a brief news conference following the meeting. “The alliance has the spare capacity, the will, and the responsibility to act when the orderly functioning of the market is at risk. We have done so today.”

Prince Abdulaziz, flanked by UAE Energy Minister Suhail al-Mazrouei, said the additional barrels would be phased in beginning April 7 and reach full volume by mid-May. He said the agreement would be reviewed at OPEC+’s next regular ministerial meeting in early June and could be extended, scaled back, or unwound depending on conditions in the Strait of Hormuz and the trajectory of the conflict.

The communique made no direct reference to Iran, a founding OPEC member whose own crude exports have collapsed in recent weeks. But the political subtext was unmistakable. Three delegates, speaking on condition of anonymity because the discussions were private, said the Iranian delegation had warned Riyadh and Abu Dhabi in private bilaterals on Monday evening that a large production hike would be interpreted in Tehran as an “economic alignment” with Washington and Tel Aviv. The Saudi and Emirati delegations, the people said, were unmoved.

“For the first time in years, the Saudis have effectively voted against Iran inside the room,” said John Reilly, a senior commodities strategist at Citi. “Whatever they say about market stewardship, this is a political document as much as an economic one. It tells the United States that the Gulf will pay part of the cost of containing a war it has every reason to want ended.”

Russia’s deputy prime minister for energy, Pavel Sorokin, who had cautioned over the weekend against “premature interventions,” briefly addressed reporters before flying back to Moscow. He described the agreement as “a calibrated response” but pointedly declined to endorse the framing offered by Prince Abdulaziz.

That last point cut to the heart of the technical critique that hung over the meeting. Roughly a fifth of the world’s seaborne crude moves through the Strait of Hormuz, and the bulk of Saudi, Emirati, Kuwaiti and Iraqi exports must pass through the chokepoint to reach Asian and European refineries. U.S. Navy escort operations have restored some commercial transit in recent days, but tanker insurance rates remain near multi-year highs and several major shipowners continue to refuse new voyages to Gulf loading terminals.

“You can announce 1.5 million barrels, but you have to put them on water,” said Helima Croft, head of global commodity strategy at RBC Capital Markets. “The question is not whether the Saudis have the wellhead capacity, which they obviously do. The question is whether Hormuz will let those barrels out. Until that question is settled, the discount to physical delivery is going to keep widening.”

To address that concern, the communique announced a parallel coordination mechanism with the International Energy Agency, which is expected on Wednesday to authorize the release of an initial tranche of 90 million barrels from member-country strategic petroleum reserves over the next 60 days. IEA Executive Director Fatih Birol, speaking in Paris, called the combined response “the most significant supply intervention since the agency’s founding.”

President Donald Trump, in a post on his social media platform shortly after the Vienna announcement, praised the decision as “a great win for American drivers” and credited “tough, smart diplomacy” by his administration. Energy Secretary Chris Wright said in a statement that the United States would “match the alliance’s resolve” with a phased release of 30 million barrels from the U.S. Strategic Petroleum Reserve.

The Iranian oil ministry issued a brief statement in Tehran denouncing the agreement as “an unlawful intervention in sovereign market mechanisms.” Iranian Foreign Minister Abbas Araghchi, in Islamabad for the continuing Turkey-mediated peace talks, declined to address the OPEC+ decision directly but told reporters that “those who profit from war should not expect to also be its arbiters.”

S&P 500 futures climbed more than 1.7 percent in evening trading following the announcement, and Asian equity benchmarks opened sharply higher Wednesday morning. Gold, which had touched a record above $3,400 an ounce on Monday, eased back below $3,330. U.S. retail gasoline prices, which had pushed above $4.60 a gallon in recent days, were forecast by the Energy Information Administration to ease toward $4.20 by mid-April if Brent stabilized in the $108 to $112 range.

Officials in Vienna said a follow-up technical meeting of OPEC+ market monitoring committee members had been scheduled for April 14 to review compliance and assess whether additional barrels might be required.