Republican presidential candidate John McCain has welcomed Tuesday's announcement on U.S. troop withdrawals from Iraq, while Democrat Barack Obama has sharply criticized it.

Presidential nominees: Senator John McCain (l) and Senator Barack Obama (r)

McCain said the announcement by President George Bush, a fellow Republican, demonstrates the success of U.S. efforts in Iraq.  He said the announcement makes clear that the planned withdrawal is based on conditions on the ground and the advice of U.S. military commanders.

But Obama said the U.S. continues to spend $10 billion a month in Iraq while the Iraqi government has a $79 billion surplus.  He said the absence of a timetable for withdrawal continues to give Iraq's leaders a "blank check" instead of pressing them for reconciliation. 

McCain described Obama as "utterly confused" by the progress in the war.  Obama said McCain talks about change, but is running for "four more years" of the same foreign policy as that of the Bush administration.

Obama has pledged to pull combat troops out of Iraq in 16 months if elected, while McCain promises to base any decision on troop levels on conditions on the ground and the advice of military commanders.