Joint Chiefs of Staff Chairman Gen. Hugh Shelton has told the commander of U.S. peacekeeping forces in Kosovo that only under "extraordinary" circumstances should American troops be sent out of the sector they are patrolling to back up other international peacekeeping forces, a Pentagon spokesman said today. Shelton sent a letter on Feb. 20 to Gen. Wesley Clark, the commander-in-chief of U.S. European Command, after 350 American troops were sent last week to Metrovica in Northern Kosovo, an area under...