ISIS is a force for evil that poses an imminent security threat to the United States, but please, let us get back to you on whether we are determined to defeat it.

That is the posture of the Obama administration toward the terror group that proudly demonstrated its malevolence by beheading American journalist James Foley in a propaganda video.

For the administration, ISIS isn’t merely a dire enemy, it is a dilemma. President Barack Obama must respond to a group that — with its resources, apocalyptic vision and Western recruits — is clearly a threat to the homeland, at the same time he wants nothing to do with Iraq in particular or any new military intervention in general.

The default Obama strategy, then, will be to do the minimum necessary not to be accused of allowing ISIS to run riot. If he must launch a few airstrikes to arrest ISIS’s sweep toward Kurdistan, he will. If he must make a statement about the beheading of James Foley before hitting the links on his vacation, he will.

But he is loath to commit himself. In his Foley statement, the president sought to sound stalwart without saying anything in particular. He brought down the hammer of History with a capital “H” on ISIS. He said, “People like this ultimately fail.” He asserted that “the future is won by those who build and not destroy.” He pronounced a global consensus around the proposition that a group like ISIS “has no place in the 21st century.”

All reasonable, forward-looking people agree that genocide has no place in the 21st century, either. Yet the prospective slaughter of Yazidis trapped on Mount Sinjar after fleeing ISIS wasn’t stopped by the inevitable progress of international norms, but (to the administration’s credit) by American bombs in conjunction with Kurdish fighters on the ground.

At a press briefing last week, Chairman of the Joint Chiefs Martin Dempsey and Secretary of Defense Chuck Hagel sounded like they were setting the intellectual and rhetorical predicate for a broader campaign — before it was all tacitly walked back.

Gen. Dempsey said that ISIS “will eventually have to be defeated” and that it couldn’t be rolled back without hitting it in Syria. Then, a few days later, he made it clear that he opposes hitting it in Syria.

Hagel said that ISIS is an “imminent threat,” a statement that White House spokesman Josh Earnest refused to back up a few days later.

If the administration is too forthright about ISIS, it closes off escape hatches for the president, who as an anti-Iraq War purist has a consistent record of not wanting to grapple with this particular threat.

He opposed the surge under George W. Bush that defeated al-Qaida in Iraq, the precursor to ISIS. He had no interest in keeping U.S. troops in Iraq that might have helped preserve those gains. When the Syrian civil war began to rage, he refused to robustly support the relatively moderate opposition, thus ceding the ground to what became ISIS.

Iraq is now doubly reminiscent of the Vietnam War. First, the collapse of American political will to maintain forces in Iraq, even after we had defeated the insurgency, recalled the end of Vietnam.

Now, the administration’s de facto policy of graduated escalation — progressing from a strictly limited mission to protect the Yazidis and American personnel potentially threatened in Kurdistan to something more extensive, yet still amorphous — recalls the beginning of the Vietnam War.

The administration must fear where the logic of a war against ISIS leads. If it is prosecuted in earnest, it means a bombing campaign against the group on both sides of the Syria-Iraq border, and quite possibly American boots on the ground. In other words, the kind of “escalation” that would have brought howls of outrage from Democrats in the Bush years, and especially from then-Sen. Obama.

He must decide how badly he wants to win his Iraq War.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.