President Trump said on Friday that he was “strongly considering” imposing sanctions and tariffs on Russia until a cease-fire and permanent peace deal was reached in its war with Ukraine.

In his announcement, which was posted on his social media site, Truth Social, Mr. Trump said he was “strongly considering” imposing what he described as “large scale” sanctions, including on banks, because of the perilous state of the war, now in its fourth year.

His post came as Russia unleashed a furious bombardment aimed at critical Ukrainian infrastructure overnight on Thursday and on Friday. Ukraine’s energy minister, German Galushchenko, said Russian forces launched a “massive missile and drone” assault on power and gas facilities across the country.

“Based on the fact that Russia is absolutely “pounding” Ukraine on the battlefield right now, I am strongly considering large scale Banking Sanctions, Sanctions, and Tariffs on Russia until a Cease Fire and FINAL SETTLEMENT AGREEMENT ON PEACE IS REACHED,” Mr. Trump wrote. “To Russia and Ukraine, get to the table right now, before it is too late.”

New sanctions would be the latest turnabout for Mr. Trump’s management of the war in Ukraine. He has spent weeks aligning himself with President Vladimir V. Putin’s narrative of the war, criticizing Ukraine for being invaded by Russia, and accusing President Volodymyr Zelensky of Ukraine of being the “dictator” who didn’t want peace.

Mr. Trump and Mr. Zelensky have spent recent days smoothing over tensions after an explosive Oval Office meeting last week, which resulted in Mr. Zelensky’s leaving the White House without signing a deal that would grant the United States a share of its revenues from mining rare earth metals.

Following the meeting, the United States halted military aid to Kyiv, as well as intelligence sharing, in an effort to pressure Ukraine to resume negotiations. In his post on Friday, Mr. Trump urged Mr. Putin and Mr. Zelensky to “get to the table right now, before it is too late.”

But Mr. Trump has basically ignored Russia’s role as the aggressor in the war, and been elusive about what Moscow ultimately wants to broker a peace deal.

Speaking from the Oval Office on Friday, Mr. Trump said he believed that Mr. Putin wanted to end the war and would “be more generous than he has to be.” Mr. Trump then suggested that it was Ukraine that would be more difficult to work with.

“In terms of getting a final settlement, it may be easier dealing with Russia,” he said, “which is surprising, because they have all the cards, and they’re bombing the hell out of them right now.”

Asked whether he believed Mr. Putin was taking advantage of the U.S. pause of military aid to Ukraine, Mr. Trump appeared to defend his decision to do so, saying that he thought “he’s doing what anybody else would do.” Mr. Trump also said he would not provide air defenses to stop Russia’s “pounding” until he knew that Ukraine would “settle.”

“If they don’t want to settle, we’re out of there,” he said, “because we want them to settle.“

Russian officials met last month with top Trump officials in Saudi Arabia, though Russia has not given any public indication that it would accept any truce, cease-fire or end to the war it started three years ago.

But U.S. officials have said Russia has shown openness to continuing discussions. On Thursday Mr. Trump said that he believed they would make a deal because “in a certain different way — a different way that only I know, only I know — they have no choice.”

The Biden administration imposed numerous sanctions on Moscow, seeking to cripple the Russian economy and choke off its funding for its invasion, most recently targeting Russia’s energy sector and its “shadow fleet” of oil tankers.

Mr. Trump’s announcement on Friday came as many business leaders and government officials in Moscow have been expressing optimism that American sanctions would be lifted soon.

The head of Russia’s main industrial lobbying group said on Friday that he had discussed the lifting of sanctions with the head of the American Chamber of Commerce in Russia. Sanctions against Russia’s aviation industry and the potential return of Russian banks into the Western-led global bank transfer system were discussed, Aleksandr Shokhin, the head of the lobbying group, told Tass, a Russian state news agency.

But Oleg Kouzmin, chief economist at Renaissance Capital, a Moscow investment bank, said that Mr. Trump’s Friday threats made it clear that “the situation remains very uncertain, and the future is unwritten.”

Ever since the United States first imposed sanctions on Russia more than a decade ago, Moscow has honed the art of circumventing them. Russian cities are full of Western goods, be they luxury cars or everyday consumer items. And with the help of third countries — most of all China, Turkey and Central Asian states — Russian companies, including airlines, have been able to buy new equipment and service their old parts.

The United States could still try to target Russia’s “shadow fleet” of tankers Moscow has been using to deliver oil to its customers. But such a move would also likely increase the price of oil, as has happened before. For any oil sanctions to be fully effective, the United States would need to solicit cooperation from China and India, which have emerged as the top buyers of Russian crude.

U.S. and Ukrainian officials confirmed Thursday that Ukraine would send a delegation to meet with “military representatives of countries that are ready to make greater efforts to reliably guarantee security within the framework of ending this war.”

Mr. Zelensky said the Ukrainians would insist at next week’s meeting on a number of commitments from Russia to test whether a lasting peace could ultimately be reached. Those demands include Russian pledges not to attack Ukraine’s energy or other civilian infrastructure; a truce for missiles, bombs and long-range drones; and no military operations in the Black Sea. Mr. Zelensky said the meeting was scheduled for Tuesday, but did not specify who would attend.

“Ukrainians truly want peace, but not at the cost of giving up Ukraine,” Mr. Zelensky said. “The real question for any negotiations is whether Russia is capable of giving up the war.”

Ivan Nechepurenko contributed reporting from Tbilisi, Georgia, and Nataliya Vasilyeva from Istanbul.