As is his wont, President Obama is treating the border crisis — more than 50,000 unaccompanied children crossing illegally — as a public relations problem. Where to photo op and where not. He still hasn’t enunciated a policy. He may not even have one.

Will these immigrants be allowed to stay? Seven times was Obama’s homeland security secretary asked this on “Meet the Press.” Seven times he danced around the question.

Presidential press secretary Josh Earnest was ostensibly more forthcoming: “It’s unlikely that most of those kids will qualify for humanitarian relief. . . . They will be sent back.” This was characterized in the media as a harder line. Not at all. Yes, those kids who go through the process will likely have no grounds to stay. But most will never go through the process.

These kids are being flown or bused to family members around the country and told to then show up for deportation hearings. Why show up? Why not just stay where they’ll get superior schooling, superior health care, superior everything? As a result, only 3 percent are being repatriated, to cite an internal Border Patrol memo.

Repatriate them? How stone-hearted, you say. After what they’ve been through? To those dismal conditions back home?

The steel border fence and a U.S. Border Patrol observation tower are seen from Nogales, Arizona. (Nancy Wiechec/Reuters)

By that standard, with a sea of endemic suffering on every continent, we should have no immigration laws. Deny entry to no needy person.

But we do. We must. We choose. And immediate deportation is exactly what happens to illegal immigrants, children or otherwise, from Mexico and Canada. By what moral logic should there be a Central American exception?

There is no logic. Just a quirk of the law — a 2008 law intended to deter sex trafficking. It mandates that Central American kids receive temporary relocation, extensive assistance and elaborate immigration/deportation proceedings, which many simply evade.

This leniency was designed for a small number of sex-trafficked youth. It was never intended for today’s mass migration aimed at establishing a family foothold in America under an administration correctly perceived as at best ambivalent about illegal immigration.

Stopping this wave is not complicated. A serious president would go to Congress tomorrow proposing a change in the law, simply mandating that Central American kids get the same treatment as Mexican kids, i.e., be subject to immediate repatriation.

Then do so under the most humane conditions. Buses with every amenity. Kids accompanied by nurses and social workers and interpreters and everything they need on board. But going home.

One thing is certain. When the first convoys begin rolling from town to town across Central America, the influx will stop.

When he began taking heat for his laxness and indecisiveness, Obama said he would seek statutory authority for eliminating the Central American loophole. Yet when he presented his $3.7 billion emergency package on Tuesday, it included no such proposal.

Without that, tens of thousands of kids will stay. Tens of thousands more will come.

Why do they come? The administration pretends it’s because of violence and poverty.

Nonsense. When has there not been violence and poverty in Central America? Yet this wave of children has doubled in size in the past two years and is projected to double again by October. The new variable is Obama’s unilateral (and lawless) June 2012 order essentially legalizing hundreds of thousands of illegal immigrants who came here as children.

Message received in Central America. True, this executive order doesn’t apply to those who came after June 15, 2007. But the fact remains that children coming across now are overwhelmingly likely to stay.

Alternatively, Obama blames the crisis on Republicans for failing to pass comprehensive immigration reform.

More nonsense. It’s a total non sequitur. Comprehensive reform would not have prevented the current influx. Indeed, any reform that amnesties 11 million illegal immigrants simply reinforces the message that if you come here illegally, eventually you will be allowed to stay.

It happens that I support immigration reform. I support amnesty. I have since 2006. But only after we secure the border.

Which begins with completing the fencing along the Mexican frontier. Using 2009 Government Accountability Office estimates, that would have cost up to $6.6 billion. Obama will now spend more than half that sum to accommodate a mass migration that would have been prevented by just such a barrier.

But a fence is for the long term. For the immediate crisis, the answer is equally, blindingly clear: Eliminate the Central American exception and enforce the law.

It must happen. The nightmare will continue until it does. The only question is: How long until Obama is forced to do the obvious?

Read more from Charles Krauthammer’s archive, follow him on Twitter or subscribe to his updates on Facebook.