Ukraine’s long-awaited spring offensive against the Russian invasion has been postponed for so long that it has been given a new name. It’s going to be a summer offensive right now, because it hasn’t started yet.

Ukrainian officials claim the delay is not a setback. After spring rains turned battlefields into a sea of ​​mud, they decided they’d rather wait for more guns to arrive from the west.

But the slippage reflects a bigger truth: Ukraine’s struggle to expel the Russian occupiers will likely take years, not months.

In February 2022, Vladimir Putin hoped to conquer Kiev within weeks. Ukraine’s unexpected resistance, fueled by a hastily improvised stream of Western aid, upended that plan and led to a year of struggle.

Ukraine and its allies have been preparing a major counter-offensive for the past six months. But even Ukraine’s most enthusiastic supporters do not expect the campaign to end the war any time soon.

Russian troops have built formidable defenses, including extensive trenches and minefields. In land warfare, attack is usually more difficult than defense, especially against entrenched opponents.

The summer offensive could well run until the end of 2023 and lead to a long and grueling war of attrition.

So officials of the Biden administration are adjusting military aid programs for a longer period of time.

The United States, along with our allies and partners, is committed to supporting Ukraine’s defense today and tomorrow for as long as necessary, Secretary of State Antony J. Blinken said Friday. The goal, he added, is to strengthen Ukraine for years to come.

Officials say the goal is to counter Putin’s openly stated strategy of fighting until the United States and other Western countries have had enough of the conflict and pull the plug on Ukraine’s military aid.

Western weapon packages once focused almost exclusively on artillery and anti-aircraft systems that Ukraine needed to stop the Russian advance. Now they contain more sophisticated systems that can help Ukraine defend itself long after the summer offensive.

The best example is the F-16 fighter jet, which U.S. officials have long argued Ukraine didn’t need. President Biden agreed last month to allow European countries to transfer F-16s to Kiev and train Ukrainian pilots in the United States, but the planes will not arrive before the end of the year. US officials say it is; the fighters are provided for future defense, not for the summer offensive.

Other long-term weapon packages include 30 Leopard tanks promised by Germany, but which will arrive again after the summer.

At a NATO summit next month, US and European officials are expected to offer Ukraine a formal deterrence and defense partnership, including long-term commitments for military aid. The idea is modeled in part on the US partnership with Israel, which comes with 10-year arms commitments.

It is also a stopgap to sidestep Ukraine’s pleas for full membership in the North Atlantic Treaty Organization, a status that would oblige the US and other alliance members to join the war directly. Biden has ruled that out.

In any case, the new focus on long-term guarantees is another sign that the war is likely to be long.

Ukraine’s official goal is to expel Russian troops from all areas they have occupied since 2014, including Crimea. The US plans to focus on more practical goals: enabling Ukraine to defend itself and convincing Russia that the war is a lost cause.

Blinken and other US officials have said the outcome of the war will ultimately be determined by negotiations between Ukraine and Russia, but they hope Ukraine will gain strength only after a summer offensive.

In any case, neither side seems willing to negotiate anytime soon.

Putin will likely decide to fight on, said Alexander Vershbow, a former US ambassador to Russia. And the vast majority of Ukrainians are against giving up any territory.

The summer offensive will also have political consequences in the West. If Ukraine succeeds, it will bolster Western confidence that the war is worth fighting. If the offensive fails, it will revive doubts in the West and encourage Putin to keep fighting.

Public support for the war has eroded in the West over the past year, but polls show a slim majority or majority still support continued military aid. Government officials have tried to bolster US support by arguing that the war is about more than just Ukraine.

How many times in history have aggressors who have taken possession of a neighboring country or part of it been satisfied and stopped there? asked Blinken, implicitly drawing parallels with the Second World War and the Cold War. When has that ever satisfied Putin?

Ukrainians have borne a tragic cost in blood and treasure to defend their country. With courage and luck, their upcoming summer offensive could be a turning point, even though the war is unlikely to end.

The long-term challenge is whether the United States and Europe can be relied on to support them for years to come, as Blinken said.