President Trump is threatening to close the U.S. border with Mexico.

He made the threat on Friday — a response to surging migrant arrivals at the border — then repeated it Saturday on Twitter. On Sunday, White House officials took to the morning news shows to make it clear he wasn't kidding. As White House counselor Kellyanne Conway said on Fox News, the president's threat "certainly isn't a bluff."

Let us hope it is. Because shutting down the border probably wouldn't do much to curb illegal immigration. It will, however, have dramatic and disastrous consequences for America. As The Washington Post reports, it "would disrupt supply chains for major U.S. automakers, trigger swift price increases for grocery shoppers, and invite lawsuits against the federal government."

Any reasonable U.S. politician would avoid such a catastrophe. But we're talking about Trump here, so anything is possible.

Two things are worth noting. First, Trump's solution to the so-called "border crisis" is simply awful, as the Post's reporting points out. But perhaps more importantly, Trump is not even trying to solve the right problem.

In the minds of Trump and nationalist advisers like Stephen Miller, the issue seems to be this: "They" want to come here. (Don't know who "they" are? The weekend Fox News chyron discussing "3 MEXICAN COUNTRIES" should probably give you a good idea.) But the surge of migrant families isn't actually the problem — it's a symptom.

The real issue is that, in some countries south of the border, things are a mess — the kind of mess you and your family would probably also try to flee if you had few other choices.

Here's how UNICEF USA described conditions in Honduras, El Salvador, and Guatemala late last year: "Crushing poverty. Endemic crime. Gang-related violence, extortion, and forced recruitment. High rates of domestic violence and sexual abuse of girls. Scarce social services. Limited opportunities to learn, or to earn a living. The desire of children to be with their parents, who are already working in the U.S."

Migrants aren't headed to the United States for the sheer pleasure of angering Trump and his supporters. They're doing it to make better lives for themselves, and that is the most human of reasons.

As long as conditions remain dire in those countries, people will try to flee. And they will flee in the direction of the most hope and opportunity. For now, that seems to be the United States.

Naturally, the Trump administration announced it is cutting aid to those countries — punishing them for the conditions that have led to mass migration. This is actually the surest way to increase migration: That aid was being used to address the very problems causing people to flee. "It's a shooting-yourself-in-the-foot policy," one nonprofit official grumbled to Politico.

Cutting off aid to Central America, then shutting down the border with Mexico, makes sense only if you completely reject the idea of enlightened self-interest. Trump, it seems, is capable of analyzing actions and transactions between people only in the narrowest sense of costs and benefits, winners and losers. We have no evidence that he believes in a "win-win" situation. So moving to help improve conditions in Honduras, Ecuador, and Guatemala makes no sense to the president as a good solution to mass migration — he can see such efforts only as sunk costs.

Unfortunately, in this case, the media is playing into Trump's hands. While there are notable exceptions, there has been very little coverage of the root causes of migration. As a result, the only moment that garners attention is the moment a migrant tries to cross the border. Everything that came before that moment — the various complex reasons someone would be compelled to leave their home — is forgotten.

For much of the American public, this makes Trump's solution — shut the border down! — appear, if not reasonable, than at least sort of understandable. But it's a mistake.

The president sold himself to the American public as having a singular ability to fix the country's problems. What's increasingly clear two years on is that he's not just lousy at the fixes, he can't even be trusted to properly identify the right problems in the first place. There are probably no easy solutions to the issues that spur mass migrations. But Trump, true to character, has come out in favor of the worst possible options.