Many supporting the decision to bomb now did so for contrasting reasons. Those opposed said the U.S. never should have invaded Iraq in the first place, but they also struggled with America's obligation to the ravaged, upended nation, which has endured violence between rival Islamic sects and, recently, the ruthless onslaught of the militant group calling itself the Islamic State.
There was one constant across Americans' opinions: Nobody could envision a concrete solution to Iraq's problems.
Neil McCanon, who was deployed to Iraq for four months as an armored crewman in the Army, said the U.S. should not have gone into Iraq in 2003. "I felt like it was not really justified, and it was proven to be unjustified after we got there," he said, referring to the never-found Iraqi weapons of mass destruction, the alleged threat cited to justify the war.
But he thought Friday's airstrikes, which targeted Islamic State militants who have conquered swaths of Iraq and Syria, were the right thing to do.
"These are bad guys, there's no question about that. The only question is where do we use force and how much, I guess," said McCanon, who now is co-owner of the Virginia Beach-based Young Veterans Brewing Company.
One of the main reasons McCanon voted for Obama was because he promised to end the war. He trusts Obama's pledge not to send ground troops, but where exactly to draw the line about the use of force remains an open question for him.
"That's something I'm just conflicted on as a soldier and someone who spent time there. I don't want the place to fall into chaos," McCanon said.
Tom Lord, a 60-year-old retired firefighter from Fort Lauderdale, Florida, who was visiting Manhattan's 9/11 memorial Friday, said he supports the new bombing, even though he disagrees with most of Obama's other decisions.
"I would hope they send troops, but I don't believe Obama will. We need to go over there and establish peace again, or at least try to," he said.
Lord supported the original 2003 invasion. He thought the latest problems were a result of Obama pulling troops out too soon: "They needed to train up the Iraqis more than they did. They pulled out way too soon and now look what happened."
"There's a direct connection to that and what is happening now," Lord said, speaking near the South Tower reflecting pool, with the sound of rushing waterfalls in the background. "When you have a void, terrorists are going to fill it in."
"The U.S. needs to play mother over everybody else to lead them and guide them and take care of them," he added.
Does that mean America is still responsible for protecting Iraq, years after handing the country control of its own future?
Timothy Broxson in downtown Pensacola, Florida, answered this way: "I don't know if it is our responsibility, but I believe it is the right thing to do."
Broxson, 57, whose father and brother are military veterans, said, "I believe we should help."
"It is a slaughter," he said of the militants' advance, "and we need to do something about it."