President Joe Biden’s administration announced Friday that it’s expanding sanctions against Russia’s critically important energy sector, unveiling a new effort to inflict pain on Moscow for its grinding war in Ukraine as President-elect Donald Trump gets set to return to office vowing to end the conflict quickly.

The outgoing Democratic administration billed the new sanctions as the most significant to date against Moscow’s oil and liquefied-natural-gas sectors, the driver of Russia’s economy. Officials said the sanctions, which punish entities that do business with the Russians, have the potential to cost the Russian economy billions of dollars per month.

More than 180 oil-carrying vessels that are suspected to be part of a shadow fleet utilized by the Kremlin to evade oil sanctions as well as traders, oil field service firms and Russian energy officials are also targeted by the new sanctions. Several of the vessels targeted are suspected of shipping sanctioned Iranian oil, according to the Treasury Department.

“The United States is taking sweeping action against Russia’s key source of revenue for funding its brutal and illegal war against Ukraine,” Treasury Secretary Janet Yellen said in a statement. “With today’s actions, we are ratcheting up the sanctions risk associated with Russia’s oil trade, including shipping and financial facilitation in support of Russia’s oil exports.”

In a move coordinated with Washington, the U.K. also slapped sanctions on Russian energy firms. The U.S. and Britain are targeting two of Russia’s major oil producers, Gazprom Neft and Surgutneftegas, and dozens of the companies’ subsidiaries.

The Foreign Office said the two companies combined produce more than 1 million barrels of oil a day, worth $23 billion a year. British Foreign Secretary David Lammy said “oil revenues are the lifeblood of Putin’s war economy.”

“Taking on Russian oil companies will drain Russia’s war chest — and every ruble we take from Putin’s hands helps save Ukrainian lives,” he said.

The U.K. already has sanctioned almost 100 vessels in Russia’s oil-transporting “shadow fleet” as Ukraine’s Western allies seeking to increase economic pressure on Moscow before any negotiations on ending the war.

White House national security spokesman John Kirby said the Biden administration chose this moment — just 10 days before Biden leaves office — for tougher oil measures because worries about world oil markets have subsided.

“This was really based on market conditions,” Kirby said. “And so the time was propitious for this decision, and that’s why the president made it.”

The State Department also announced it was hitting 14 senior Rosatom officials and executives with travel bans that also affect their immediate family members.

Biden administration officials said that it ultimately will be up to Trump’s administration whether to keep or scrap the new sanctions.

Trump’s transition team did not respond to a request for comment.

Asked if the Biden administration consulted with the incoming Trump team, Kirby responded, “We have at every step and on every major issue been keeping the transition team informed of our decisions, what we’re doing and why we’re doing it.”

Trump’s incoming national security adviser, Mike Waltz, wrote in an opinion piece for the Economist published shortly before Election Day that the U.S. should “use economic leverage” for “cracking down on Russia’s illicit oil sales” to bring Russian President Vladimir Putin to the negotiating table.

Trump’s warm relationship with Putin over the years has come under heavy scrutiny.

The Republican president-elect also balked at the cost of aid to Kyiv, pledging to move quickly to end the conflict upon his return to office Jan. 20.

Trump added a new layer of doubt about future American support this week when he appeared to sympathize with Putin’s position that Ukraine should not be part of NATO.

The president-elect has criticized the Biden administration for expressing support for Kyiv’s eventual membership in the transatlantic military alliance.