An advance force of 2,600 NATO soldiers will begin moving into position in the Balkans on Sunday. Some 1,200 American troops will participate, with 700 stationed in Bosnia and another 500 in Croatia. Joint Chiefs of Staff Chairman John Shalikashvili said that the mission could cost $2 billion (the White House had estimated $1.2 billion) and that the total number of American ground troops in the region will be 32,000. About 3,500 reservists would also be called up. "Once you get away from the 20,000 troops in Bosnia," says TIME's Mark Thompson, "the numbers can be a little goofy. The best guess at this time, including the support troops, is a figure somewhere between 30,000 and 40,000 committed to the operation in Bosnia and rim countries like Hungary and Italy."