"Some of the forces that have always possibly pulled Iraq apart are stronger now, (and) those forces that could keep the country united are weaker," he told NBC Nightly News. "It is ultimately going to be up to the Iraqi leadership to try to pull the politics of the country back together again."
Obama is sending U.S. military advisers to Iraq and has threatened air strikes as Sunni Islamists have seized the north of the country and made a push toward Baghdad. Growing mistrust between Shia and Sunni Muslims has heightened tensions in the country, where the United States fought a war from 2003 to 2011, the president said.
Obama, who is under fire from some Republicans for his decision to pull U.S. troops out of the country when he did, defended his decision.
"Just because something is stable two years ago or four, doesn't mean that it's stable right now," said.