Russian dictator Vladimir Putin no longer holds the initiative in the war against Ukraine, Ukrainian President Volodymyr Zelenskyy told Fox News during last week’s visit to the United States. Numerous fellow European leaders seem to share Zelenskyy’s optimistic assessment. “Ukraine’s position is stronger than ever since the war began,” Finnish President Alexander Stubb commented in recent days.

Ukraine’s progress offers a rare window of opportunity to increase the pressure on Putin and create the conditions for a negotiated end to Europe’s largest war since World War II. However, this window is likely to prove temporary. Kyiv’s European partners must therefore seize the moment and demonstrate that they are capable of acting decisively on the international stage by increasing support for Ukraine.

The last real chance for Ukraine to end the war came in the final weeks of 2022. The success of Ukraine’s Kharkiv counteroffensive and the liberation of Kherson had allowed Kyiv to gain the battlefield initiative, leaving Putin’s retreating army in a state of demoralized disarray. The war appeared to be entering a decisive phase, with Ukraine poised to defeat Russia’s invasion. At this critical moment, Kyiv’s Western partners lost their nerve. Their fear of escalation handed Putin a lifeline.