Faced with U.S. demands to provide the military muscle to enforce a future Ukraine peace deal, Europe finds itself in a bind.

Experts say that sending European peacekeepers to Ukraine might stretch and weaken NATO¡¯s own defenses, and that the mission would still need U.S. support to succeed.

While U.S. boots on the ground may not be necessary, deterrence in the form of U.S. medium-range missiles and ultimately nuclear weapons will remain crucial.