Immigration and Customs Enforcement launched a nationwide sweep — ostensibly designed to catch Central Americans who’d come to the US as family units — in late July. But according to the press release they sent out Tuesday, 70 percent of the immigrants they captured were merely collateral damage.

The statement said that of the 650 immigrants nationwide, fewer than 200 of those people were actually targeted in the operation: 73 members of family units, and 120 (former) unaccompanied children. The other 457 people — nearly three-quarters of those caught up in the sweeps — were simply “also apprehended” and arrested.

This is a stunning admission from the Trump administration. Even in the most generous accounting, that means more than half of the immigrants picked up in last week’s ICE raids hadn’t been targeted and didn’t have criminal records.

President Donald Trump’s ICE agents picked up a few hundred immigrants just for being in the wrong place at the wrong time. They were arrested, and now will presumably be put in deportation hearings, because they happened to cross paths with ICE agents looking for somebody else.

This isn’t a prospect that unauthorized immigrants had to worry about during the last years of the Obama administration. And historically, it’s not something the federal government has had the capacity to do. But the Trump administration can, and is deliberately stoking the fear that it will. It wants those in the country without legal status to feel unsafe, even if they haven’t been targeted for deportation.

The sweep is something of a last hurrah for outgoing Homeland Security Secretary John Kelly — who the president named his chief of staff last week. But while the staggering arrest totals seem at first to reflect a promotion-worthy immigration record, the disconnect between who ICE said they were targeting and who they originally picked up is a clue to the truth. Kelly’s management success as head of DHS — the signal policy success of Trump’s administration — is simply that he allowed immigration agents to do what they wanted: arresting whichever unauthorized immigrants they happened to find.

Collateral arrests are the Trump administration’s most powerful weapon to arrest unauthorized immigrants without warning

Collateral arrests were known to happen under the Obama administration. But generally, ICE agents were under instructions to arrest people identified in advance, and only those people.

Under Obama, DHS leadership took pains to distinguish between unauthorized immigrants who should be prioritized for deportation — “felons” with criminal records or recent entrants — and members of “families” who’d lived in the US peacefully for years. While collateral arrests during immigration operations were known to happen under Obama, ICE agents were generally under instructions to arrest people identified in advance — and only those people.

Many ICE agents hated this. They felt they were being prevented from doing their jobs; on a daily basis, they interacted with people who were deportable under federal law, and weren’t able to try to deport them. As much as anything, collateral arrests symbolized the “handcuffs” that agents felt shackled in under Obama — and which Trump immediately set about taking off once he arrived in January, with the enthusiastic support of then-Homeland Security Secretary John Kelly.

The results are clear. When the Obama administration launched a series of raids targeting Central American families in January 2016, they arrested around 100 people — “most” of whom were individually tracked down and targeted. When the Trump administration continued the operation in last week’s sweeps, they caught about twice as many targets — and 450 immigrants as “collateral.”

The combination of nationwide, coordinated raids and collateral arrests is something immigrants didn’t see in the Obama era. Now, they’ve seen them twice under Trump — and with this latest operation, the “collateral” arrests, any way you slice them, are exceeding the arrests of immigrants that ICE is ostensibly going after.

This is the immigration record that impressed Trump enough to appoint John Kelly chief of staff

When the sweeps were conducted, retired Marine Gen. John Kelly was secretary of Homeland Security. By the time ICE announced the results, Kelly had been sworn in as White House chief of staff — thanks, in large part, to how impressed Trump has been with DHS’s record on immigration enforcement during Kelly’s time there.

Kelly is being promoted, in other words, for the kind of things that ICE did last week — or at least for running a department where agents felt free to arrest hundreds of immigrants as collateral.

That distinction is extremely important. The hope of appointing Kelly to manage a fractious White House appears to be that Kelly’s military experience and demeanor will “discipline” the factions warring for influence with the famously mercurial president. But if Trump thought he saw the ability to do that when he looked at Kelly’s DHS tenure, he was exactly wrong. The difference between the Obama-era Central American raids and these wasn’t John Kelly — it was the freedom for ICE agents in the field to do their jobs however they saw fit, with less concern for the collateral damage collateral arrests would do to the rest of an immigrant community.

But the other thing that attracted Donald Trump to John Kelly was Kelly’s ability to defend the Trump administration’s policies in public — often by proclaiming that the agents carrying out those policies obviously had nothing but the safety of Americans at heart, and decrying anyone who dared to question their actions. And in that regard, his experience defending operations like last week’s ICE sweep will be crucial.

If you didn’t read DHS’s statement about last week’s sweeps carefully, you would be left with the impression that they sought out and tracked down a huge number of immigrant "absconders" who’d come from Central America and been ordered deported — not that only 30 percent of the people it had ended up arresting were the people it had set out to arrest.

It’s the kind of thing the president’s base seems enthusiastic about in the new regime. And immigrants themselves, who see ICE vans (or vans that could be ICE) in their neighborhoods or see Facebook photos from people who do, are getting the message.