Mr. Biden said last month that there will be “no shortcuts” for Ukraine getting into NATO, even after the war.
No matter how the wording is worked out, NATO officials say another key element of the summit will be a demonstration of practical support for Ukraine. Mr. Putin, several NATO leaders have argued, believes Europe’s commitment will flag — and that, combined with an ammunition advantage, would ultimately lead to Ukraine’s defeat.
So the next two days will be filled with pledges, organized under a general pledge issued by some countries — perhaps the Group of 7, or a smaller group known as the Quad (the United States, Britain, Germany and France) — to which other countries will sign up, NATO-country diplomats said. The hope is to issue such a document with the pledges in Vilnius.
The document is meant to provide Ukraine with serious security commitments for the long run, even if it falls short of the security guarantee of full NATO membership. That means providing modern weapons and training that would ensure that Ukraine is so well armed that Russia would never try to invade it in the future.
Camille Grand, a former senior NATO official now with the European Council on Foreign Relations, said the challenge would be to avoid “simply repeating the vague promises of the past. We have to counter the notion that if you have a frozen conflict, you are not welcome.”
There will be another major, if symbolic, act: Ukraine’s relationship with NATO will be upgraded to “council status,” meaning that on key issues, Ukraine will be able to sit with the 31 member states as an equal, without Hungary, for example, able to block its participation. Russia once held that status until it annexed Crimea; giving it to Ukraine is a clear message to Mr. Putin.
The summit will also approve a new defense-spending pledge for the alliance, to replace the one agreed on in 2014, which aimed for allies to spend 2 percent of gross domestic product on the military, including 20 percent of that on equipment. The latest figures show that only 11 of the 31 members have reached that goal.
Still, NATO has no way to enforce those demands.
Also, and perhaps as important as anything else, the allies will give political approval to the first detailed war plans on how to defend all of NATO territory since the end of the Cold War. Those plans, drawn up by Gen. Christopher Cavoli, the American commander of allied forces in Europe, cover more than 4,000 pages and tell countries in specific terms what is required of them to defend themselves and their allies.