Washington began basing forces on European soil in the wake of World War II and during the Cold War. But some lawmakers and Defense experts say such a large U.S. military presence in Europe is no longer needed, arguing the basing arrangement is too pricey at a time when America's economy is running on fumes.

Polis said his plan would save over $800 million. Pentagon officials have not taken an official stance on the issue, but they have noted there would be immediate costs to build the facilities needed to permanently move large numbers of forces to the United States.