Last month, yet another NATO summit concluded with a vague statement that Ukraine will, at some point, be a member of the alliance.

But while it is impossible to provide a precise date for Ukraine’s accession while the country is at war, the event that should trigger it should be clear: The United States and its NATO allies should stand ready to provide full protection to Ukraine as soon as a peace deal is reached. This would enable and encourage Ukraine’s government to make the difficult choices that are needed to bring an end to the fighting.

The first step toward charting a path toward durable peace in Ukraine is recognizing that Russia did not launch its full-scale invasion in 2022 merely to take some Ukrainian territory. Nor was the goal to prevent vague promises of future NATO membership for Ukraine from being fulfilled — though the Kremlin did exploit these promises to convince Russians and others that the invasion was crucial to preempt serious threats to Russia’s security.