Across Europe, political leaders face an urgent new reality: the US may no longer be the guarantor of European defense. They're grappling with how they would pick up the slack should - as signaled by the Trump administration - Europe's security rest solely on its own shoulders. The shift in Washington's policy has strained transatlantic relations and thrown the durability of the NATO alliance into doubt. Furthering the rupture is Trump's criticism of Ukrainian President Volodomyr Zelenskyy as a