Why did Donald Trump reverse himself on Wednesday and call an end to his policy of separating migrant families detained at the southern border? It was clear from the start that the policy was cruel, heartless, and unnecessary. Although there has been a spike in the number of asylum seekers in recent months, the over-all number of undocumented immigrants coming into the United States from Mexico and other Latin American countries is significantly lower than it was a decade ago. There is no “crisis” at the southern border, except the humanitarian one of Trump’s own making. Trump’s picture of the United States being swamped—or, in his words, “infested”—by Latino migrants is a fantasy that he concocted to whip up the racial fears and antipathies of his core supporters.

Clearly, Trump didn’t make this U-turn because he had grown tired of fear-mongering and racial incitement, or because he had experienced a crisis of conscience. (It’s far from clear that he’s even capable of such a thing.) He reversed course because he had no choice politically. Although he often adopts the rhetoric and body language of an authoritarian strongman, he’s an elected politician. And in the face of mass outrage, bipartisan opposition, and condemnation from church groups and other civil-society institutions, the child-separation policy was no longer sustainable.

But Trump didn’t reverse the policy of “zero tolerance” that his Administration introduced in May, which obliges immigration agents to arrest and detain anybody who crosses the border outside an official entry point. The Times reported that the new executive order was designed “to get around an existing 1997 consent decree, known as the Flores settlement, that prohibits the federal government from keeping children in immigration detention—even if they are with their parents—for more than 20 days.” If Trump gets his way, families stopped at the border will now be detained indefinitely under the custody of ICE. That is precisely the outcome that the U.S. Court of Appeals for the Ninth Circuit deemed illegal in a 2016 ruling about the Flores settlement.

In another alarming sign, on Wednesday evening, CBS News reported that despite Trump’s executive order the Department of Health & Human Services, which runs the child-detention centers, won’t make any special efforts to reunite the families that have already been split up, and that the separated children will be dealt with under the same processes that have been in effect since May. Kenneth Wolfe, a spokesman for the Department, confirmed this to the Times, saying, “There will not be a grandfathering of existing cases.” (Later Wednesday night, the Department put out a statement saying its spokesman had “misspoke” and it was “awaiting further guidance on the matter.”)

At most, this was a very partial U-turn. If Trump’s executive order survives the inevitable legal challenges, which is far from certain, it will keep more than two thousand children away from their parents, and it could well lead to the creation of a chain of semi-permanent refugee camps on the southern border. Trump only went this far because he was facing a public-relations disaster and a rebellion from Republicans fearful of losing control of Congress in the midterms.

On Tuesday, the Senate Majority Leader, Mitch McConnell, until now Trump’s faithful enabler on Capitol Hill, stated publicly that he and his fellow Republican Senators were in agreement that the child-separation policy “needs to be fixed.” On Wednesday morning, Paul Ryan, the Speaker of the House, said that on Thursday the lower chamber would “vote on legislation to keep families together.” In the past year and a half, congressional Republicans have demonstrated that there is little they won’t do to abase themselves before Trump, if it means getting the policy results they desire. But even usually gutless pro-Trump Republicans weren’t willing to enter a campaign season defending a policy of tearing infants from their parents and keeping them detained in tents and metal cages.

A Quinnipiac University opinion poll that was released earlier this week indicated that Americans opposed the child-separation policy by an overwhelming margin, more than two to one. Only a majority of Republicans supported the policy. As The Atlantic’s Ronald Brownstein pointed out, on Twitter, white, non-college-educated white women, a key voting group for the G.O.P., were opposed to the policy by the whopping margin of fifty-six per cent to thirty per cent. And this poll was taken before the latest reports and pictures from inside the child-detention centers.

When Trump went up to Capitol Hill on Tuesday night to meet with House Republicans, he was sticking to the fallacious line that only Congress could fix the problem. Less than twenty-four hours later, he finally dropped this pretense. “We are going to be signing an executive order in a little while,” he said at the White House, at lunchtime on Wednesday. “We’re gonna keep families together. But we still have to maintain toughness, or our country will be overrun by people, by crime, by all of the things that we don’t stand for, that we don’t want.”

This statement, and similar ones he made later in the day, indicated that he intends to stick with his campaign theme of targeting undocumented immigrants, and depicting them as base creatures who could “infest” the United States. The political crisis is by no means over, nor is the migrant crisis. Until the children in the detention camps are reunited with their parents, and a reasonable system is reinstituted for dealing with families detained at the border, there is no cause for celebration.

A Crisis at the Border More coverage of the Trump Administration’s immigration policy from The New Yorker.

But at least Trump has been forced to retreat on one political front. And for that we have to thank the media, some civic and religious institutions, and the conscience of the American public. After Attorney General Jeff Sessions announced the zero-tolerance policy, in May, the number of children who were separated from their parents quickly grew. Civil-rights groups monitored the situation, and the news media began to focus on it. Before long, some religious leaders expressed concerns, and so did some elected politicians, including Senator Jeff Merkley, Democrat of Oregon, who tried to visit a detention center in Brownsville, Texas, but got turned away.

As public outrage mounted, the policy turned into a major news story. Eventually, some media organizations obtained shocking pictures from inside the detention centers, and one, ProPublica, posted an audiotape of young children crying for their parents, and an immigration agent joking about it, saying, “Well, we have an orchestra here.” In the face of these stories, all of the Trump Administration’s rationalizations, deceptions, and outright lies couldn’t hide the fact that it was carrying out an iniquitous and indefensible policy. This was real news, not fake news, and, ultimately, it forced Trump to back down.

This post was updated to include the statement issued Wednesday night by the Department of Health & Human Services.