Read the AHA Board statement on southern border policy here.

“Like animals in a cage.” That’s how a federal contractor describes the warehousing of children stripped from their parents at the border. If you’re a human whose heart stretches beyond your tribe, you must be moved by this tragedy.

If you’re a humanist, you have to respond with heart, head, and action. By dictate of the White House, innocent children are being held hostage. This is unacceptable.

The politics of this situation are plain, simple, and vile. The law, communications, and policy choices, however, are complex. Be warned: no ideal solutions exist.

First the politics. From the start, Donald Trump based his campaign on fear and hatred of immigrants. In launching his unlikely presidential bid, he branded Mexicans rapists and drug dealers and promised to build a wall on our southern border.

It was a paranoid fantasy from the start. This century’s great extralegal wave of immigration peaked in 2007 and fell by about a million before Trump took office. A border wall, if it worked at all, would address less than half of those who entered on that wave. More than a quarter were from Asia, and many entered on visas and then overstayed. About a third of them are college educated and at least half speak good English.

But “invasion” is an inflammatory political trope, and Trump and the rightwing media backing him have kept the coals glowing. Now, they’ve added napalm to the inferno.

By choosing to recast a misdemeanor—crossing the border without a visa—as a criminal offense requiring incarceration, the administration has implemented what it calls a “zero tolerance policy,” and claims, dubiously, that legal precedent thereby requires children to be separated from parents. Is it justifiable to call this hostage-taking?

More than a year ago, Trump’s chief aide, Gen. John Kelly, floated the idea of stripping children from their parents. To “deter more movement along this terribly dangerous network,” he told Wolf Blitzer on CNN, “I am considering exactly that. They will be well cared for as we deal with their parents.” In plain words, he’d snatch children from their parents to instill fear in others. That’s hostage-taking. To use children as human shields is deeply immoral. To make it US policy degrades every American. But, even if the ends cannot justify the means, at least Kelly had the pretense of a good end.

Trump reveals a more vulgar motive. First, he tweeted: “Democrats can fix their forced family breakup at the Border by working with Republicans on new legislation…” In a later tweet he lays out his ransom demand: “Any Immigration Bill MUST HAVE full funding for the Wall, end Catch & Release, Visa Lottery and Chain, and go to Merit Based Immigration. Go for it! WIN!”

How can anyone, you may wonder, support such a heartless policy? To their credit, many who have been Trump supporters do not. Rev. Franklin Graham branded the policy “disgraceful.” Republican Senator Susan Collins expressed dismay. Former First Lady Laura Bush condemns it. And even First Lady Melania Trump issued a statement saying she hates seeing children separated from their parents (although she said nothing about the policy driving that).

Still, there are many, many ordinary Republicans who stand squarely behind the president. To understand why, we must try to see the situation through their eyes. I’ve spent hours on rightwing social media and news sites so that I can offer a composite of the story they receive. Foremost is that an organized invasion from the south is under way. It is run by drug cartels that make additional money in human trafficking.

The children, they are told, are not really with parents but with coyotes who pose as their parents. It’s Obama who started this policy, and it’s Democrats who wrote the laws that Trump must follow. If the children were not separated, they’d be forced into prostitution or drug dealing in the US. The parents are selling their kids, or in some cases coming across the border with them, in hopes that having kids will expedite their phony asylum claims. And really, as Gen. Kelly, said and National Review Editor Rich Lowry recently reiterated, deterring families from making this dangerous journey is better for the children than signaling that it’s worth the risk. So, ultimately it’s a humane policy.

Of all these canards, the key one is the invasion trope. This evokes an atavistic fear that enables all the rationalization that follows. But we must acknowledge that there are grains of truth in the chaff of propaganda.

The passage is dangerous, there are coyotes (human traffickers), some children are with adults who are not their parents, and some parents who claim asylum are really economic migrants. But just as with the refugee shutdown, Trump’s argument has been that if there are any bad apples, the entire barrel must be cast aside. That may or may not make sense with apples, but you cannot treat human beings that way.

Authentic families—mostly mothers and children—are fleeing Central America for legitimate reasons. The zero-tolerance policy means that if a parent wants to claim asylum at the border, she must submit to incarceration and give up her child for as long as it takes to adjudicate her claim. That can be a very long time indeed. The stated intent is to force the parent to give up on asylum and accept deportation.

The retort from the right is that kids are separated from parents every day in the criminal justice system—and it’s true! Unfair bail laws mean that some innocent people of little means are held for long periods. But at least they’re charged with more than a misdemeanor, they have a right of family visitation, and the enforced separation is not intended to force them to plead guilty.

Immigration is a great boon to America. As a nation of ideas not bloodlines, we are exceptionally good at integrating New Americans. I see that every day in my work, but more importantly every study shows that’s true.

Still, we must accept an unpalatable truth: the United States must have effective border controls and a rational immigration policy. To borrow a phrase from political scientist John Hibbing, fear of invasion by “the tribe over the hill” is simply baked into human nature. When people sense that their borders are open, liberal democracies to give way to nativist impulses. We’ve seen it in Britain, in Italy, and worst of all in our own country.

In the short run, we may have to accept a policy of detention for border-crossing families together while their asylum claims are adjudicated. It’s unlikely that “catch and release,” as Trump calls it, will be tolerated. To press for it could hand victory to immigration hardliners in the fall elections. What we cannot and must not accept is a policy of using children as hostages for Trump’s immigration agenda.