European leaders are discussing a security guarantee for Ukraine that would commit Kyiv’s allies to decide within 24 hours whether to provide military support to the country if it’s again attacked by Russia.

A proposal that amounts to a NATO-like collective defense clause, but doesn’t come with actual membership in the alliance, is being pushed by Italian Prime Minister Giorgia Meloni. It’s among an array of options being fleshed out as European leaders leverage momentum after U.S. President Donald Trump agreed to back security guarantees for the war-battered nation.

The Italian plan recognizes that NATO membership for Ukraine is off the table, but would offer a mechanism for collective assistance as the next best option, according to people familiar with the deliberations.