For more than seventy years, Europe’s security has rested on one central assumption: when the crisis comes, the United States will be there. Not only with troops, but with bases, logistics, intelligence, airlift, command structures, deterrence, and political reassurance.But what happens when that assumption begins to change?Recent reports suggest that Washington may be preparing to accelerate the withdrawal of part of its military presence from Europe, including a previously announced reduction of around 5,000 troops from Germany. At first glance, this may look like a technical military adjustment. In reality, it touches one of the deepest questions in European security: can Europe defend itself if the American presence becomes smaller, more selective, and more conditional?