"Some of the biggest GOP cheerleaders for the disastrous war in Iraq are now joining the blame-America-first crowd rather than working with our Commander-in-Chief to confront this crisis," Boxer said in a statement Thursday.
She said the current crisis in Iraq "has its roots in an ill-conceived war," arguing that while the U.S. should "go after" the Islamic State of Iraq and Syria, the Sunni jihadi organization taking over parts of the country, "any U.S. action must be well-considered and well-executed in coordination with our allies and the Iraqi government and military, which we helped train and arm."
It's not clear who Boxer's criticism was directed at, but numerous Republicans have bashed the president for the growing crisis.
Earlier on Thursday, Speaker John Boehner (R-OH) accused Obama of "taking a nap" while terrorists take control of western Iraq.
Boxer was one of just 23 senators who voted against the October 2002 resolution to authorize the use of military force in Iraq, a move she later called one of her proudest moments as a senator.