President Obama and the Defense Department are warning of the dangers of deploying ground troops to Syria without first answering whether ISIS can be defeated without them.

Critics say the status quo is not doing the job.  Max Boot wrote in the Wall Street Journal on December 8 that air power alone cannot defeat ISIS.  The same morning, former Army Chief of Staff retired General Ray Odierno likewise told MSNBC’s “Morning Joe” that air power has never won any war in history, and added that “[y]ou can’t defeat ISIS without having people on the ground.”

On the other hand, Gen. Paul Selva, Vice-Chairman of the Joint Chiefs of Staff, testified before the Senate Armed Services Committee the next day that, “[i]t’s clear from ISIL’s strategy that their objective is to cause us to engage in what they believe is an apocalyptic war with the West.”  Selva added, “anything that we do to feed that particular frame of thinking counters our national security.”

Gen. Selva’s assertion that ISIS wants a US or allied Western ground incursion may be true, as far as it goes.  William McCants of the Brookings Institution reported more than a year ago about ISIS’s eschatological vision, writing that ISIS’s Summer, 2014, campaign was designed in part to capture the militarily insignificant town of Dabiq precisely because “[ISIS] members believe the great battle between infidels and Muslims will take place there as part of the final drama preceding the Day of Judgment.”  ISIS places enough faith in the prophecy that it named its slick online magazine “Dabiq.”

And it is fair to assume that non-Muslim troops fighting the self-declared Caliphate reborn will attract recruits, including some who might not have joined the battle but-for foreign boots on the ground.

Even if true, though, this simply does not respond to the point that air power alone cannot defeat ISIS.  The Administration’s critics are not necessarily even advocating deploying ground troops, but are pointing out that air strikes on their own cannot defeat ISIS.  These are statements of fact, not recommendations.

And for all his heated objections about the dangers of deploying ground forces, Gen. Selva never addressed whether they would be necessary to defeat ISIS.  He certainly implied that the cost of ground troops is so high it should not be considered, but that does not answer the question.

But the DOD is only reiterating the President’s policy position, and in any event is handicapped by his failure to articulate clear goals.

“Degrade or destroy” makes for a handy sound-bite, but what does that mean for developing strategy and identifying the required resources?  Killing ISIS members certainly degrades the organization temporarily, and the DOD has resorted to releasing body-counts.  Yet there has been little measurable progress in defeating ISIS.

The first question that has to be answered is, what conditions are we trying to achieve on the ground.  Then, what resources are required to achieve that result?

The President must answer the first question and hasn’t.  Until he does, the Pentagon cannot provide a complete answer to the second.