According to Donald Trump, the caravan of migrants walking north from Guatemala toward the United States harbors "unknown Middle Easterners," who are no doubt intent on committing terrorist outrages of the most dastardly sort upon Americans once they penetrate our inner sanctum.

Except, of course, there is zero evidence that such "unknown Middle Easterners" exist anywhere but in the swirling mind beneath Trump's trademark swirling hairstyle. He means to terrify, to scare people until they can't think straight and to give them a focus for fears that stay unspoken. As he constantly demonstrates, if he can magnify that fear by telling atrocious lies, he will eagerly do so.

Trump tells these lies because it is all he knows. He doesn't know how to govern – handing him the powerful tools of government and asking him to craft solutions is like handing a hammer to a chimp and asking him to repair your computer. Whatever problems you might have, he's about to make them worse.

In this case, those thousands of migrants – many with young children – are not attempting a grueling walk of some 1,200 miles over rough territory because they have been hired as part of some Democratic international conspiracy to overturn American sovereignty and swamp the voting booths, as Trump has suggested and as some ridiculously believe. They are doing it out of desperation, because they have no hope if they stay and so are gravitating toward where hope might be. History tells us that very few will make it; they have just begun a 1,200-mile journey through rough terrain, and most will turn back.

But think about it: What would it take for you, personally, to even begin such a journey, on foot, with your family in tow, taking only the possessions that you could carry on your back? What level of desperation would that require? Whatever your personal answer, that's the level that these people have now reached. That's the root cause of this problem, and unless you acknowledge and address that cause, you cannot hope to solve it.

Now consider the main policy response offered so far by Trump. Because the governments of Honduras, Guatemala and El Salvador have been unable to keep their people at home, within their borders, he says he will punish them by slashing if not eliminating foreign aid.

He doesn't seem to comprehend that if those governments had the resources and stability to take effective action, their people wouldn't be fleeing north in the first place. Stripping U.S. aid will further weaken those countries and their economies, driving an acceleration of their citizens' out-migration. In fact, foreign aid to those three poverty-stricken countries is already being cut. Thanks to Trump, in fiscal 2019 it is slated to fall by some 40 percent compared to when Trump took office in 2016, for a grand total of $181 million for all three.

That's a reflection of another Trump instinct, to pretend that the United States can isolate itself from the rest of the world. We can build trade walls through tariffs, we can build literal walls to close off our borders, we can tell allies that they are no longer needed nor appreciated, we can substitute punishment for generosity and we can be safe inside our little cocoon.

Well, no, we can't. Those thousands of people trying so desperately to reach our border are the world's way of telling Trump that it isn't true. We can't punish them into submission, nor can we ignore them. We can deal with them where they are, helping to make their home countries livable, or we can deal with them here.

– Jay Bookman is a columnist for the Atlanta Journal-Constitution.