The first and most obvious way for Ukraine to win would be for its armed forces to take back all the territory Russia has unlawfully seized since its first invasion in 2014 — including Crimea. This would be a fantastic outcome. It is still possible. And the United States should do everything possible to support it, including, if Congress approves more funding, by providing the more advanced weapons Ukraine has requested.

At the same time, if we’re honest, we have to acknowledge that Ukraine may not achieve total military success in the next year or two. Its counteroffensive is making progress, but slowly and painfully. The Russian military, though battered and demoralized, has remained resilient, even against advanced Western weapons and tactics. And Russia has a seemingly endless supply of young men whose lives it is willing to waste in this war.

Meanwhile, there is no guarantee that the United States and its allies will continue paying for Ukraine’s offensive operations for as long as it takes. Getting Biden’s recent supplemental funding request for Ukraine through the House of Representatives will be hard, and that money would last only through early 2024. Putin knows that the leading Republican candidate for president next year, former President Donald Trump, would end U.S. support for Ukraine, and that there are others like him in Europe. A forever war favors Putin, not Ukraine.

A second way for Ukraine to win — at least theoretically — would be through a diplomatic agreement. Earlier this month, 40 countries, including China and the United States, met in Saudi Arabia to discuss President Volodymyr Zelenskyy’s 10-point plan for peace, which would require the withdrawal of all Russian troops from Ukraine, the return of abducted children and justice for war crimes. Any settlement based on that plan would, of course, be wonderful.

But Russia under Putin has never ended its wars at the negotiating table; at best it has frozen them, keeping its options open. Russia has shown zero interest in making concessions that would come close to the minimal requirements of Ukraine and its allies. As long as his military avoids total collapse, and he believes there is a chance of political change in the West, Putin will likely keep sacrificing Russians to stay in the fight.

So if Russia manages to stymie plans A and B, where would that leave us by, say this time next year? Should Ukraine and its allies simply carry on, hoping for a breakthrough in 2025 or beyond? Given what’s at stake — not just the survival of Ukraine but of the whole international order — that would be risky. It would make success dependent on events we cannot predict or control, including on the outcome of elections in Western countries, including the United States. And while we have no right to tell Ukrainians to stop fighting before their country is whole, we also have no right to expect them to keep fighting at any cost.

Fortunately, there is a third possible way to satisfy the need for Ukrainian success and Russian failure, over which Putin would have no veto.

In this scenario, the United States would give the Ukrainian military whatever it needs to advance as far as possible in its counteroffensive. At an appropriate point next year, Ukraine would declare a pause in offensive military operations and shift its primary focus to defending and rebuilding liberated areas while integrating with Western institutions. Then, at its July, 2024 summit in Washington, NATO would invite Ukraine to join the Western alliance, guaranteeing the security of all territory controlled by the Ukrainian government at that point under Article 5 of the NATO treaty.

Offering Article 5 protection to Ukrainian territory in this fashion would be akin to admitting a divided Germany to NATO after World War II and to America’s security pact with South Korea after the armistice that halted the Korean War without reunifying the Korean Peninsula. This would be a defensive pact, but not a commitment to take direct part in any future offensive operations Ukraine might choose to undertake.

The Biden administration has said the war must end before Ukraine can join NATO, because it does not want to risk direct U.S. involvement. But it has not defined what it means, in this context, for the war to be “over.” Must there be a formal peace treaty? Must there be a period of months or years in which Russia does not fire a single shell into Ukraine? Tying Ukrainian NATO membership to such conditions would give Putin another incentive never to meet them.

But Ukraine joining NATO could itself be how the war ends, consistent with Biden’s current policy — and at a time and on terms set by Ukraine and its allies, not by Russia. Gaining security within NATO as a strong, pluralistic, democratic state would absolutely count as a victory for Ukraine — arguably as big as quickly regaining Crimea. It might make it politically possible for Zelenskyy, if he so chooses, to emphasize nonmilitary strategies for reclaiming any parts of his country still under Russian occupation, which Ukraine’s allies would also continue to support — potentially including anything from diplomacy and sanctions to blockade and sabotage.

Adding a democratic Ukraine in NATO would mark the utter and permanent defeat of Putin’s crusade to absorb it into a Russian empire. Because it would be hard to reverse after ratification by 32 NATO member parliaments, NATO accession — ideally by the end of 2024 — would also frustrate Putin’s plan to draw out the war until political winds in the West change.

Yes, Russian forces could try to go on the offensive again, but the likely futility of attacking fortified Ukrainian positions now backed by the threat of NATO firepower would be a strong deterrent. Meanwhile, sanctions on Russia would remain; its economic and military strength would continue to erode; and Putin could only watch as his frozen assets abroad are drawn down to pay for Ukraine’s reconstruction. He would be left with no agency and no options.

To be clear: this approach would not require Ukraine to cede any territory to Russia (contrary to what a NATO official suggested this week). Ukraine and its allies would continue to pursue the country’s reunification within its 1991 borders. Nor should anyone pressure Ukrainians to adopt this approach — only they can decide whether and when shifting to consolidating their gains while joining NATO makes sense.

But Biden and other Western leaders should tell them that this is an option they will have if their counteroffensive is still grinding on next year. It could prove the best chance to achieve the victory that Ukraine and the democratic world need soon, while making it both Putin- and Trump-proof.