Ally, Member or Partner? NATO’s Long Dilemma Over Ukraine.

BRUSSELS — Ukraine presents NATO with a dilemma many years in the making — one the alliance, itself, helped create.

In 2008, NATO — an American-led alliance explicitly created to counter the Soviet Union — promised membership to two former Soviet republics, Ukraine and Georgia, but without specifying when or how.

Russia saw the offer as a potential threat on its borders and an encroachment into the heart of its sphere of influence, the most serious in a series of affronts and humiliations by the West since the fall of the Soviet Union. From the outset, some NATO nations questioned whether the offer of membership was a wise move, and it is not clear that the promise will ever be kept, but predictably, it has fed a lasting conflict with President Vladimir V. Putin.

With Ukraine a NATO partner but not a member, it does not benefit from NATO’s core principle, the commitment to collective defense, though Ukraine has sent troops to fight in NATO missions in both Iraq and Afghanistan.

So, as thousands of Russian troops mass on Ukraine’s borders, NATO is not bound by treaty to protect Ukraine militarily, nor is it likely to try. Asked on Wednesday about the possibility of dispatching U.S. forces to Ukraine, President Biden flatly ruled it out, telling reporters at the White House, “That is not on the table.”

But NATO does have a compelling interest in trying both to deter Russia and to avoid provoking an invasion.

“It is important to distinguish between NATO allies and partner Ukraine,” Jens Stoltenberg, the NATO secretary-general, said last week. “NATO allies, there we provide collective defense guarantees,” while “Ukraine is a partner, a highly valued partner.”

But what does NATO owe such a highly valued partner?

“The question that NATO faces at its core is how it maintains the credibility of the alliance,” said Ivo Daalder, a former U.S. ambassador to NATO and president of the Chicago Council on Global Affairs. For all its closeness to NATO, he said, Ukraine is not a member, so “how do you still guarantee its independence and sovereignty?”

Marta Dassu, a former Italian deputy foreign minister and adviser on Europe to the Aspen Institute, said, “You can’t explicitly accept Putin’s proposal to rule out membership in NATO, so in the end you try to build up Ukraine’s military deterrence but can resort only to more economic sanctions, and that’s probably not enough.”

The Biden administration has sounded alarms recently about a possible Russian invasion of and has warned Moscow that serious economic penalties would follow. Mr. Biden said he had made that clear to Mr. Putin in a two-hour video conference the two leaders held on Tuesday.

“If, in fact, he invades Ukraine, there will be severe consequences — severe consequences — and economic consequences like none he’s ever seen or ever have been seen,” Mr. Biden said.

After the meeting, Mr. Putin repeated his contention that NATO expansion to Ukraine would pose a grave threat to Russia, and that “it would be criminal negligence on our part” not to seek to stop it.

“Russia carries out a peace-loving foreign policy, but it has the right to assure its own security,” Mr. Putin said at a news conference in Sochi. “We assume that this time, at least, our concerns will be heard.”

He spoke about discussion, not invasion. Russia would present proposals to Washington about a security dialogue in the next week, he said, adding: “We have the chance to continue this dialogue. I believe that this is the most important thing.”

Over the past generation, a dozen countries that were once part of the Soviet bloc have joined NATO, moving its boundaries hundreds of miles eastward — expansions that Moscow has taken as aggressive moves by a potential enemy.

Given the promise of membership, Mr. Putin sees “encirclement” and a still-expansionist NATO that is committed to ripping Ukraine away from the Russian zone of influence. That is a particularly difficult blow for a man who saw the breakup of the Soviet Union as “the greatest geopolitical catastrophe” of the last century, and has focused on rebuilding and reasserting Russian power.

Mr. Putin regards Ukraine, where the medieval Russian state was born, as a fake country and an “inalienable part of Russia.” He laid out his views in a long essay in July, “On the Historical Unity of Russians and Ukrainians.”

Rightly or wrongly, he “increasingly views Ukraine as a Western aircraft carrier parked just across from Rostov Oblast in southern Russia,” wrote Eugene Rumer and Andrew S. Weiss of the Carnegie Endowment, noting that Ukraine is now one of the largest recipients of American military aid.

So far, Mr. Putin’s attempts to restore Russian control over Ukraine have backfired. In 2014, after a Ukrainian revolt that caused its pro-Russian president, Viktor F. Yanukovych, to flee, Mr. Putin invaded and annexed Crimea and aided a separatist war in eastern Ukraine that continues to this day.

“Putin is not being provoked by NATO, he’s provoked by the independence of Ukraine,” Mr. Daalder said. “But he’s made it less likely that Ukraine will ever do what he wants because of his actions. Ukraine is more pro-Western and more Ukrainian, and less Russian, as a result of what Putin did in 2014.”

In Ukraine’s 2019 elections, pro-Russian candidates were crushed. Mr. Putin runs the risk that invading Ukraine, rather than producing the submissive neighbor he wants, would, as many believe, simply reinforce Ukraine’s desire to remain independent.

After the collapse of the Soviet Union and the Warsaw Pact, some in the West suggested NATO disband as well. Instead, it expanded, and once it began, “it was hard to know when to stop,” said Lawrence Freedman, emeritus professor of war studies at King’s College London and author of “Ukraine and the Art of Strategy.” Of course, he noted, the expansion was in response to the desires of the countries of the former Soviet bloc.

It would have been better, Mr. Freedman suggested, if NATO had “found other ways to support Georgia and Ukraine” and not promised membership. Most likely Ukraine will never be integrated into NATO, he said, “but we can’t put that into a treaty,” as Mr. Putin demands.

Still, it may be easier to grant Mr. Putin the discussion he says he wants on the future of European security if it eases Russian fears, Mr. Freedman said. “Fine, let’s have a big conference, it could go on for years. Talking to Putin is not a concession.”

But NATO’s “cardinal sin,” as Mr. Daalder put it, was the undefined promise made to Ukraine and Georgia in Bucharest in April 2008, the result of a late-night compromise reached by former President George W. Bush when other NATO members, like Germany and France, rejected his proposal to offer the two countries a concrete and immediate road map to membership.

“The Bucharest compromise was the worst of both worlds,” said Carl Bildt, the former Swedish prime minister and foreign minister. “It created expectations that were not fulfilled and fears that are grossly exaggerated. It was short-term expediency with long-term consequences that we have seen since then” — in Georgia, which lost a quick and nasty war to Russia four months later in 2008, and in the Russian effort to destabilize and even reassert control over Ukraine.

Fiona Hill, a Russian expert at the Brookings Institution, was at the Bucharest summit as an American national intelligence officer. She said the intelligence community recommended against offering a membership path to Ukraine and Georgia, because much of NATO opposed it, but it was overridden by Mr. Bush.

The compromise was brokered by the British, she said, but “it was the worst of all possible outcomes.” Mr. Putin, she said, “has been trying to shut that door ever since.”

Anton Troianovski contributed reporting from Moscow.