The chairman of the Senate Foreign Relations Committee says the killing of Osama Bin Laden is a potential game-changer that could lead to greater stability in Afghanistan and bringing U.S. troops home.

Sen. John Kerry, D-Mass., made the comments at the start of a hearing on Afghanistan.

Kerry says a precipitous U.S. troop withdrawal would be a mistake. But the U.S. should be working toward a smaller force that puts Afghans in charge, he said.

Kerry said it was unsustainable to continue spending $10 billion a month with no end in sight.