Will Biden’s Help for Ukraine Come Fast Enough and Last Long Enough?

During 27 months of war in the heart of Europe, President Biden has consistently resisted pressure from many of his allies to let Ukraine into NATO, convinced that it was the one step that could quickly result in American troops being sent into direct combat with Russia, a war he fears could escalate and even turn nuclear.

So on Thursday, he rolled out a new set of alternative steps, each designed to demonstrate to President Vladimir V. Putin of Russia, and to the Ukrainians, that the United States and its allies have no intention of packing up and leaving, as they did in Afghanistan, even if Ukraine remains outside NATO for years.

He signed a 10-year security pact — albeit one with vague commitments and an early exit option — with Ukraine’s president, Volodymyr Zelensky. Mr. Biden portrayed the agreement as a long-term guarantee of continued arms, intelligence support, advice and technology to win the current war and deter a new one.

And he said the United States would take the lead in providing a loan of about $50 billion to Ukraine to rebuild its devastated ports and power plants, buy weapons and close its budget gap. The money is to be repaid from interest generated from $300 billion in assets that Mr. Putin, inexplicably, left in Western financial institutions before his February 2022 invasion.

“Our goal is to strengthen Ukraine’s credible defense and deterrence capabilities for the long term,” Mr. Biden said moments after he and Mr. Zelensky signed the accord on the southwest coast of Italy, where the Group of 7 industrialized nations opened their annual leaders conference.

“We’re not backing down,” he added, warning Mr. Putin that “he cannot wait us out.”

Mr. Zelensky thanked Mr. Biden warmly, even though the security pact and loan were far short of what he wanted at this grave moment in the war. Mr. Zelensky has made no secret of the fact that it is hard to focus on Ukraine’s long-term prospects when he is desperately worried about surviving the short term in the face of relentless, if incremental, Russian advances.

But the bigger worry for Ukraine’s increasingly embattled leader, and for all of Europe, is that the accords themselves may not survive the outcome of the American election and Europe’s recent one.

The security pact, based on similar, decade-long commitments to Israel, contains no funding — just an American commitment to work with Congress to secure the tens of billions of dollars that would be required. That most likely means another bruising fight on Capitol Hill, where a bare majority of Republicans in Congress had for months opposed any more commitments of funds and the arms they buy before funding was approved in April.

But the bigger concern for Mr. Zelensky is that Mr. Biden, with whom his relationship has often been contentious, might be at his last Group of 7 summit. And buried in the fine print of the security agreement they signed with flair lies this paragraph: “Either Party may terminate this Agreement by providing a written notification through diplomatic channels” that would “take effect 6 months after.”

That is exactly the kind of loophole that former President Donald J. Trump exploited with the Iran nuclear agreement, which he abandoned in 2018. Mr. Trump has made no secret of his disdain for Ukraine or his desire to rid the United States of a huge financial commitment there. Instead, he has insisted he could end the war in 24 hours — presumably by telling Mr. Putin he can keep the territory he has already seized.

“It’s an agreement that really captures the moment,” said Seth G. Jones, director of the Transnational Threats Project at the Center for Strategic and International Studies, a prominent research institute in Washington, who just returned from a visit to Ukraine. “On the one hand, it’s a useful step to establish a long-term relationship with Ukraine. On the other hand, it is very much short of what the Ukrainians really want: real NATO membership” that, unlike the piece of paper both men signed with such flair, is hard to revoke.

The $50 billion loan, if disbursed this year, is harder for a future president to reverse. And the money is coming just in time: Ukraine’s budgetary situation is so dire that it has been forced to sell some state assets.

Treasury Secretary Janet L. Yellen, an architect of the loan plan that leaves Russia’s principal untouched but uses the interest it earns, said at an event in New York on Thursday that it demonstrated to Mr. Putin that Ukraine’s allies were “completely united.”

“We intend to give Ukraine the resources it needs to wage an effective war against Russia and to support their direct budget needs, and we’re going to provide a very meaningful chunk of resources,” she said.

“This is the first tranche, and if necessary there’s more behind it,” Ms. Yellen said. “In a sense, we’re getting Russia to help pay for the damage it’s caused.”

The president of the European Commission, Ursula von der Leyen, said on Thursday that all the members of the Group of 7 countries would participate in the loan, and the European Union might contribute up to half the money, a senior European official said. Washington would make up the difference.

But the loan is in a race against time and Russia’s destructive capability.

For the first two years of the war, it was assumed time was on Ukraine’s side — that Mr. Putin would have to back down if the war stretched on too long. Now, no one is so sure that is still the case.

Until recent days, the Russians for months appeared to have the momentum — though now they have been slowed after Mr. Biden, reversing himself, allowed Ukraine to shoot American-provided weapons onto the Russian side of the border near Kharkiv. Mr. Biden and his aides called it a “common sense” move, denying Mr. Putin the chance to attack Ukraine without fear of retribution.

The reversal was also born of the fear that the Ukrainian leader was running out of options. He is clearly short of troops and air defenses. He may be short of time.

Ukraine’s currently precarious position is notably different from what it was a few months into the war in 2022, when it seemed as if Russia’s military was collapsing. In 2023, there was hope that a Ukrainian “counteroffensive” would push Moscow’s forces out of the country. It flopped.

On Thursday, for all the talk of sticking with the war “as long as it takes,” there was little discussion, at least within earshot of reporters, of what a realistic endgame might look like. The new security accord refers to a “just and lasting peace” without defining what that means — or what happens if a just peace is in tension with a lasting one.

Mr. Putin also seems to have a remarkably high tolerance for pain — or at least the suffering of his troops.

More than 1,000 Russian soldiers were either killed or wounded on average each day in May, senior NATO and Western military officials said on Thursday. Ukraine’s forces are increasingly stepping up offensive operations as more Western military aid finally reaches the battlefield, after months of delay.

One Western military official said that Russia’s assault against the northeast city of Kharkiv has “culminated” and was not expected to continue to advance in the immediate future, and that Ukrainian strikes on artillery bases inside Russia were beginning to degrade its attacks.

But a senior NATO official, who provided an assessment at a briefing, said Russia was expected to “wage a pretty significant push” in coming weeks in a likely bloody rebuttal to any of Ukraine’s revived military capabilities. And Russia, the official said, would love nothing better than to mar the celebration of NATO’s 75th anniversary in Washington next month.

“None of us should be under the illusion that it’s going to be an easy summer,” the official said.

Only after surviving that, and the coming election, will Mr. Biden and Mr. Zelensky be able to jointly think about what Ukraine’s long-term future might look like. Otherwise, all bets are off, including how long the partnership they agreed to on Thursday will actually last.

Lara Jakes contributed reporting from Brussels, Eric Schmitt from Washington and Steven Erlanger from Bari, Italy.