The announcement of Alexey Navalny’s death on Friday thrust fresh urgency into the roiling debate in Washington over how forcefully to counter Russia and its president, Vladimir Putin, a question of wide-ranging consequence on which President Joe Biden and his likely opponent Donald Trump have adopted diametrically opposed positions.

For Democrats and a minority of Republicans who are proponents of a muscular American presence in Europe within the NATO defense alliance, Navalny’s death served as yet another grim reminder of Putin’s brutality and the necessity of a US-led effort to isolate Moscow.

But for skeptics in the Trump camp, it was far from clear whether even the death in a notoriously brutal prison camp of Putin’s leading critic would alter a hardening view that Russia’s aggression no longer requires robust western reprisals, and that the nearly 80-year-old US-led security architecture in Europe is outdated.

The stakes could hardly be higher, and Biden warned forcefully from the White House this week that “history is watching” the debate unfold.

The decision US politicians make in the coming weeks and months on whether to continue sending assistance to Ukraine could dramatically alter the battlefield realties there and send a global signal of American willingness not only to push back on Russia but to involve itself abroad at all.

Top Biden administration officials wasted little time pinning blame on Navalny’s death directly on Putin, even as the Kremlin said it was working to determine the cause.

“Whatever story they tell, let us be clear Russia is responsible and we’ll have more to say on this later,” Vice President Kamala Harris said at the start of an address at the Munich Security Conference, where American support for Ukraine and to its NATO commitments has been a central and pressing topic of conversation.

A few moments earlier, Secretary of State Antony Blinken linked Navalny’s death directly to Russia’s president.

“His death in a Russian prison and the fixation and fear of one man only underscores the weakness and rot at the heart of the system that Putin has built,” the US top diplomat said at the start of a meeting with Indian officials on the sidelines of the Munich gathering.

Lingering just underneath those pronouncements was the reality that in the United States, the long-held consensus on the value of alliances and systems to guard against Russian aggression is fraying.

Trump has shattered orthodox thinking

Trump, who seems to be reveling in undermining what had been a bipartisan consensus in American foreign policy for more than 70 years, has said he would encourage Russia to attack NATO allies who “didn’t pay” — a remark that sent shockwaves through the defense alliance, which had already been bracing for his potential return to office in 2025, but was hardly surprising to his followers.

Republican House Speaker Mike Johnson and fellow Republicans have refused to consider a spending package that includes around $60 billion in new funding for Ukraine, despite administration warnings that Ukrainian troops are running out of ammunition and failing to support Kyiv would amount to a victory for Putin. Even so, Johnson said in a statement Friday that Putin “is likely directly responsible” for Navalny’s death.

And Tucker Carlson, the former Fox News host with a major conservative following, returned from an interview with Putin last week (which even Putin complained was too soft) proclaiming how much nicer and cleaner Moscow was than any American city. Trump has reportedly mused about selecting Carlson as a running mate.

A select number of Republicans have sought to guard against the growing strain of isolationism within their party. On Friday, Trump’s sole remaining competitor for the Republican presidential nomination, former South Carolina Gov. Nikki Haley, assailed her opponent for saying he would encourage Russia to invade other nations.

“Think about what that says, that Trump’s siding with a thug who kills his political opponents. By the way, he killed another one this morning,” Haley said on a South Carolina radio show. “He’s siding with Putin, who continues to try and destroy America at every turn.”

For Biden and his top officials, the assault on international norms and institutions has generated both fury and concern. Biden was aghast at Trump’s remark when he learned about it last weekend and condemned it as “dumb” and “un-American” in a speech from the White House on Tuesday.

A campaign issue

On Friday, the Biden campaign unveiled a new digital ad blasting Trump’s comment.

“Every president since Truman has been a rock-solid supporter of NATO - except for Donald Trump,” a narrator says as images of Trump with Putin flashes across the screen. “Trump wants to walk away from NATO. He’s even given Putin and Russia the greenlight to attack America’s allies.”

Part of a three-week, six-figure digital ad campaign, the spot is set to run through Super Tuesday targeting voters in the battleground states of Michigan, Wisconsin and Pennsylvania. The campaign said it was looking to reach more than 2.5 million Americans who identify as Estonian, Finnish, Latvian, Lithuanian, Norwegian and Polish — all NATO countries bordering Russia.

In 2021, Biden emerged from his first (and, so far, only) face-to-face meeting with Putin to say he had warned his counterpart that he’d be punished if Navalny were to die in prison.

“I made it clear to him that I believe the consequences of that would be devastating for Russia,” Biden said in Geneva, where the summit was held.

Since then, the United States and its partners in Europe and Asia have piled sanctions on Russia for its invasion of Ukraine, seeking to isolate the country from the global financial system and ratchet up costs on the perpetrators of the war.

But it’s those same sanctions that have caused energy prices to rise in Europe and taken a toll on the global economy, lending grist to some Republican efforts to halt foreign funding for Ukraine’s military and urge an immediate end to the conflict.

As American assistance for Ukraine wavers, defense officials have warned of the consequences on the battlefield. On Friday, an official told reporters the US is “sixteenth in the world” among the countries providing security assistance to Ukraine when considering the percentage of GDP.

“At this point, the United States is — we’re not the top donor to Ukraine when it comes to security assistance, or economic assistance for that matter,” the official told reporters. “When you look at security assistance, we’re actually the sixteenth in the world when it comes to percentage of GDP. So we have a lot to appreciate from our allies and partners.”

Harris, who was already preparing to provide reassurances to rattled allies during her visit to the Munich conference this week, sought to underscore American commitment to protecting democracy and freedom around the world, and took veiled aim at Trump for suggesting otherwise.

“They suggest it’s in the best interest of the American people to isolate ourselves from the world, to flout common understandings among nations, to embrace dictators, and adopt the repressive tactics and abandon commitments to our allies in favor of unilateral action,” Harris said in her remarks at the yearly gathering of US and European leaders, which has traditionally acted as a citadel of transatlanticism.

“Let me be clear—that worldview is dangerous, destabilizing and indeed shortsighted,” she said.

Shortly after Harris left the stage, Navalny’s wife made a surprise appearance in Munich to urge the international community to fight against Putin’s “horrific” regime.

“They will be brought to justice, and this day will come soon,” she said.

CNN’s Haley Britzky and Lauren Fox contributed reporting.