Mr. Obama, in a televised statement before he boarded Marine One to begin a trip to North Dakota and California, emphasized that the problem was not just a short-term threat to the Iraqi government but also a long-term failure by Baghdad leaders to achieve political reconciliation across sectarian lines. He warned Iraqi leaders that if they want American help, they have to come up with a plan to accommodate minority factions in a meaningful way.

“The United States is not simply going to involve itself in a military action in the absence of a political plan by the Iraqis that gives us some assurance that they’re prepared to work together,” he said. “We’re not going to allow ourselves to be dragged back into a situation in which while we’re there we’re keeping a lid on things” but the political leaders fail to address the underlying fissures dividing Iraqi society.

Mr. Obama said he would “consult with Congress” about possible airstrikes in Iraq, but he did not say whether he would seek a vote by lawmakers as he did last fall when he was contemplating airstrikes against Syria in retaliation for the Assad government’s use of chemical weapons against its own citizens.

In this case, the original congressional authorization for the invasion of Iraq in 2003 has never expired, so he would have a different legal basis than he had with Syria.