The president who gained office by running against the Iraq War has now authorized new military action in that haunted country, an operation with limited goals that may be hard to define and attain.
President Obama outlined his objectives as protecting U.S. personnel and facilities from a militant army in Iraq, and rescuing religious minorities besieged by the same group of jihadists.
The bigger goal: keeping U.S. military activity limited and avoiding another full-scale commitment in Iraq.
"I ran for this office in part to end our war in Iraq and welcome our troops home, and that's what we've done," Obama said in announcing his plans Thursday night. "As commander in chief, I will not allow the United States to be dragged into fighting another war in Iraq."
Analysts said achieving those limited aims may be difficult, as the United States and its Iraqi allies confront a jihadist force that has swept through large parts of Syria and northern Iraq.
"It's about picking between bad options and less bad options at this point," said Sam Brannen, a senior fellow at the Center for Strategic and International Studies and a Pentagon official during the Obama administration.
While Obama has resisted previous calls to take action against the Islamic State of Iraq and Syria (ISIS), he felt increased pressure in recent days as ISIS fighters approached the province of Irbil, the base for U.S. personnel and facilities that aid the Iraqi army.
The militants, also known as the Islamic State of Iraq and the Levant (ISIL), are also laying siege to a group of religious minorities who live on a mountain in northern Iraq. Obama authorized air drops of food and water to stave off a potential genocide, casting it as a core (and limited) national security interest.
"When we have the unique capabilities to help avert a massacre, then I believe the United States of America cannot turn a blind eye," Obama said. "We can act, carefully and responsibly, to prevent a potential act of genocide."
Eventually, the United States would like to turn over the fighting to Iraq's security forces, but there are questions about their quality in the face of the ISIS invasion.
"We could be in this game for a long time," said Douglas Ollivant, a senior fellow with the New America Foundation and director for Iraq at the National Security Council during the Obama and George W. Bush administrations.
Neither Obama nor his aides defined how to judge whether airstrikes against ISIS are successful. The president did say that "American combat troops will not be returning to fight in Iraq, because there's no American military solution to the larger crisis in Iraq."
Lawmakers expressed general support for current operations, but some worried the air strikes could lead to more expansive operations.
"I oppose open-ended military commitments, which the President's actions in Iraq could become," said U.S. Sen. Richard Blumenthal, D-Conn.
While supporting the humanitarian relief effort to stop genocide, Blumenthal said that Obama "owes the American people a better, fuller explanation of the scope and strategy of military actions."
House Minority Leader Nancy Pelosi, D-Calif., said she supported the president's immediate actions in Iraq but added that "I was pleased by the president's continued assurances that he will not send U.S. troops back into combat in Iraq."
There's no American military solution in Iraq, Pelosi said, and Iraq's leaders need to "see beyond their divisions and come together to fight this common threat."
White House spokesman Josh Earnest said new U.S. plan will be evaluated regularly, but "the president has not laid out a specific end date." He said Obama is determined to avoid a prolonged U.S. military commitment.
Other lawmakers say Obama isn't going far enough to stop ISIS.
Two Republican senators — John McCain of Arizona and Lindsey Graham of South Carolina — issued a statement saying that Obama's plans do not go far enough to meet the "expansionist" militant threat.
"The president needs to devise a comprehensive strategy to degrade" the militant army, they said. "This should include the provision of military and other assistance to our Kurdish, Iraqi and Syrian partners."
That's not on Obama's agenda. "I've been careful to resist calls to turn time and again to our military, because America has other tools in our arsenal than our military," he said. "We can also lead with the power of our diplomacy, our economy and our ideals."
Kenneth Pollack, a senior fellow at the Brookings Institution, said he supports the president's immediate plan, but called the first moves "tactical" initiatives that lack an overall strategy.
Pollack, who worked on Iraq issues during the Bill Clinton administration, said lack of a U.S. strategy could result in an all-out civil war in Iraq, one that could spread to neighboring nations in the Middle East.
"These civil wars don't stay contained," Pollack said. "This is all dangerous stuff."