After the briefing, Gibbs went to the president for clarification. Gibbs then called me to his office to relate what the president said. The president told him it IS locked in – there is no flexibility. Troops WILL start coming home in July 2011. Period. It's etched in stone. Gibbs said he even had the chisel.
White House: July 2011 Is Locked In for Afghanistan Withdrawal - Political Hotsheet - CBS News