John Kerry said the fight against IS militants required global effort.
Mr Kerry, on a Middle East tour, said IS Militants was the “single greatest threat” the people of Iraq now face.
He said there would be a global plan to defeat IS, but the new Iraq government must be the “engine” of that fight.
IS has seized large areas of northern Iraq, overrunning the army and gaining backing from some disaffected Sunnis. Meanwhile, at least 13 people died in a series of car bombs in east Baghdad.
The explosions happened minutes apart in the Shia neighbourhood of New Baghdad. At least 25 others were injured.
John Kerry says world cannot watch IS evil spread
Source: BBC News