French President Emmanuel Macron has become the latest leader to warn a major Russian assault in eastern Ukraine is imminent. If that’s the plan, its troops risk repeating at least some of the mistakes made in trying to take the capital, Kyiv.

According to European and NATO diplomats familiar with the matter, Ukraine’s allies see a two-week window to spirit in heavier weapons like tanks before Russian President Vladimir Putin unleashes an offensive designed to declare some sort of victory by the May 9 anniversary of Nazi Germany’s defeat in World War II.

Moscow traditionally holds a large annual military parade that day. The Kremlin did not respond to a request for comment on the potential significance of the date in the timing of the war.