When NATO’s leaders gather this summer to celebrate the 75th anniversary of their military alliance, the last thing they want to see is a resurgent Russian military marching across Ukraine because Europe was too weak to provide Kyiv with the support it needed.

What Ukraine wants, ultimately, is a formal invitation to join NATO. But alliance officials agree that is not going to happen at the festivities planned for Washington in July. NATO has no appetite for taking on a new member that, because of the alliance’s covenant of collective security, would draw it into the biggest land war in Europe since 1945.

That has sent NATO searching for some middle ground, something short of membership but meaty enough to show that it is backing Ukraine “for the long haul,” as Jens Stoltenberg, the NATO secretary general, put it this week.

What that will be has so far proven elusive, according to senior Western diplomats involved in the discussions.

Proposals put forward this week at a meeting of foreign ministers in Brussels to give NATO more control over coordinating military aid, financing and training for Ukraine’s forces were immediately met with skepticism. The United States and Germany remain opposed to offering Ukraine a start to membership negotiations in Brussels as they did at last year’s summit in Vilnius, and they want that issue off the table in July, despite a similar process at the European Union that was approved last winter. But they do want to provide Ukraine with specific commitments they can deliver on. Efforts to clearly define what conditions Ukraine needs to meet to begin talks with NATO have yet to move forward.