AS A candidate, Donald Trump pledged “zero tolerance for criminal aliens,” a stance, stripped of its tough-guy rhetoric, that might not have represented too drastic a departure from President Barack Obama’s prioritization of undocumented felons for deportation. Within days of taking office, however, Mr. Trump issued an executive order that expanded the definition of criminality so broadly as to encompass virtually any undocumented immigrant charged with a crime or even suspected of having broken a law.

In sweeps by immigration agents across the country, the new administration seemed to be making good on Mr. Trump’s threat by arresting more than 600 undocumented immigrants, most of them in metropolitan areas in a dozen or so states. While the actions by Immigration and Customs Enforcement (ICE) in themselves were not dissimilar to raids undertaken during the Obama administration — which in the 2012 fiscal year alone resulted in the deportation of more than 400,000 people — they unleashed a wave of anxiety in immigrant communities. For good reason, they feel they are in the new president’s crosshairs.

That anxiety was fed by reports, subsequently confirmed by ICE officials, that along with unauthorized immigrants who had committed serious crimes, others were caught in the dragnet if they happened to be in the wrong place at the wrong time, lacking papers.

In a conference call with reporters, David Marin, a top ICE official in Los Angeles, justified the raids by saying that “dangerous criminals who should be deported are being released into our communities.” At the same time, though, he cast doubt on his own assertion by acknowledging that about 40 of the roughly 160 undocumented immigrants detained by ICE agents in the Los Angeles area had been convicted not of felonies but of misdemeanors — and in a few cases had no criminal convictions at all. It’s anyone’s guess how those 40 count as “dangerous criminals who should be deported.”

The president says he will hire 15,000 additional immigration officers and Border Patrol agents, if Congress will pay for them, and advocates for undocumented immigrants are braced for more sweeps. Immigration courts, already so clogged that hearings are scheduled 18 months and more in advance, may face a fresh deluge of detainees.

It is sensible policy to target undocumented immigrants who are convicted felons, especially repeat offenders, for deportation. Gang members who have committed violent crimes, drug traffickers and others who represent a genuine threat to public safety should be found and sent packing, as they were during the Obama administration.

It is hard to imagine what purpose is served by focusing on immigrants with clean records, unless instilling terror in immigrant communities is the goal. Of the estimated 11 million illegal immigrants, most have been in this country for more than 15 years. Roughly 8 million of them are in the workforce. Large numbers have children, spouses and other relatives who are U.S. citizens or legal permanent residents. They are part of this country’s fabric, and to deport them en masse is wrong.