The U.S. ambassador James F. Jeffrey says the Obama administration remains open to the idea of keeping thousands of American troops in Iraq next year if asked, despite a spike of deathly attacks on soldiers by Shiite militias.

Ambassador James F. Jeffrey emphasized Saturday that no decision has been made by Washington. Baghdad's Shiite-led government has not asked to extend the U.S. troop presence, though it is widely expected to do so.

Jeffrey says U.S. troops appear to be the militias' top target now, but that attacks will continue against Iraqis if the American military leaves.

Fifteen U.S. soldiers died in Iraq in June, nearly all of them killed by Shiite militiamen. It was the bloodiest month for Americans troops in two years, according to Associated Press.