Oil rallied the most in more than a year after OPEC+ unexpectedly announced output cuts that threaten to tighten the market and deliver a fresh inflationary jolt to the world economy.

The world’s most important oil price is about to be transformed, allowing crude supplies from West Texas to help determine the price of millions of barrels a day of petroleum transactions.

Oil headed for the longest stretch of weekly losses this year as central banks around the world stepped up the fight against inflation at the cost of economic growth.

The U.S. may begin refilling its emergency oil reserve when crude prices dip below $80 a barrel, according to people familiar with the matter.

West Texas Intermediate crude futures dropped below $100 a barrel for the first time since May 11 as concerns grow that a global economic slowdown will ultimately hobble demand.

The Biden administration is considering triggering tougher anti-smog requirements that could curb drilling across parts of the Permian Basin, the world’s biggest oil field that straddles Texas and New Mexico.

Oil extended gains after the close as a decision by the U.S. and other major economies to release emergency stockpiles failed to ease concerns of a major shortfall in supplies as sanctions mount on Russia.

Oil surged above $105 a barrel for the first time since 2014 after Russia attacked sites across Ukraine, triggering fears of a disruption to energy exports at a time of already tight supplies.

The U.S. Department of Energy announced the loan of 13.4 million barrels of crude oil from its strategic reserve as part of a renewed effort by the Biden administration to contain oil prices that have surged to their highest level since 2014.

Demand for oil is nearing pre-COVID levels and producers globally are investing too little in supply, Saudi Aramco said.