President Biden personally blamed President Vladimir V. Putin of Russia on Friday for the death of jailed Russian dissident Aleksei A. Navalny and cited the case in pushing House Republicans to approve military aid to Ukraine in its war with Moscow.
But while he once threatened to impose “catastrophic” consequences on Mr Putin if Mr Navalny died in prison, the president admitted there was little he could do after sanctions and other actions taken over the past two years in response to the invasion of of Russia in Ukraine.
“Make no mistake: Putin is responsible for Navalny’s death,” Mr. Biden said in a televised statement from the White House. “Putin is responsible. What happened to Navalny is yet another proof of Putin’s brutality. No one should be fooled, not in Russia, not at home, not anywhere in the world.”
Asked whether Mr Navalny had been assassinated, Mr Biden said the United States did not have a full understanding of the circumstances. “The answer is that we don’t know exactly what happened, but there is no doubt that Navalny’s death was the result of something Putin and his thugs did.”
Mr Navalny’s death came at a delicate moment in America’s confrontation with Russia over its aggression in Europe and repression at home. House Republicans have blocked $60.1 billion in military aid to Ukraine ordered by former President Donald J. Trump, who himself boasts that he would “encourage” Russia to attack NATO allies who don’t spend enough on their armed forces.
Mr. Biden is seeking to bolster American leadership in the world and reassure European allies that the United States still has their back. He sent Vice President Kamala Harris and Secretary of State Antony J. Blinken to the Munich Security Conference in Germany this week to allay fears of an American retreat. But the mood in Munich was dark even before reports of Mr Navalny’s death. American attendees said that wherever they went, they were besieged by upset Europeans.
“What we want to hear are real assurances that the Americans are not going to abandon Ukraine and Europe,” Wolfgang Ischinger, a former German ambassador to the United States and a longtime conference influencer, said before Ms. Harris’ speech. “There is panic in this country.”
Ms Harris sought to make just such assurances, although there was much skepticism in the room, where many were already bracing for the prospect of a second term for Mr Trump if he wins the November election.
“In these turbulent times, it is clear: America cannot back down,” Ms. Harris told the conference. “America must stand strong for democracy. We must defend international norms and rules, and we must stand by our allies. This represents the ideals of America, and the American people know that this is what makes us strong. And make no mistake, the American people will come together right now and America will continue to lead.”
Speaking in Washington, Mr. Biden cited Mr. Navalny’s death to push his case to Congress to pass security aid to Ukraine and expressed outrage that the House adjourned without taking action.
“It’s about time they stepped up, don’t you think?” he said. “Instead of going on a two-week vacation. Two weeks! They go away. Two weeks! What are they thinking? Oh my god. This is strange. And it just reinforces all the concern and almost, I won’t say panic, but real concern about the United States being a reliable ally. This is outrageous.”
It was unclear exactly what had happened to Mr Navalny, but no one in the Biden administration was taking seriously the official explanation that he had simply passed out and died after taking a walk in his Arctic prison. If he was killed, American officials should think about what it says about Mr. Putin right now. With events seemingly turning out in Washington of late, some analysts said, Mr. Putin may have felt greater impunity to act against his most prominent domestic challenger without fear of retribution.
Almost three years ago, Mr Biden said he had warned Mr Putin, during a meeting in Geneva, not to harm Mr Navalny while he was in prison, adding that no one would buy Russian covers if he turned up dead . . “I made it clear to him that I think the consequences of this would be devastating for Russia,” Mr. Biden told reporters after the meeting in 2021.
“What do you think is going on when he says it’s not to hurt Navalny, all the things he says to justify his treatment of Navalny, and then he dies in prison?” Mr. Biden said then. “It’s a matter of trust. It’s about their ability to influence other nations in a positive way.”
But the president admitted Friday that it would be difficult to bring about those “catastrophic” consequences because, in the years since, Russia’s invasion of Ukraine had prompted the United States and the West to impose broad sanctions and other sanctions on Moscow. Still, Mr. Biden said, “we’re looking at what else we can do.”
Mr Biden said Mr Navalny’s death should remind Americans of the importance of standing up to Mr Putin and hit out at Mr Trump, who appears likely to be his challenger, for encouraging Russia to attack allies. Mr. Biden, calling it a “dangerous statement,” pledged to stand with Europe against Russian aggression.
The president praised Mr. Navalny’s courage in returning to Russia even after he was poisoned and knew that returning would put him at risk of being sent to prison, which he did.
“There were so many things that Putin was not,” Mr. Biden said. “He was brave, he was principled, he was dedicated to building a Russia where the rule of law existed and where it applied to everyone.”
Stephen Erlanger contributed to the report.
