When things aren’t going smoothly for President Trump, his go-to move is to change the subject to topics that cheer his supporters and drive his critics into paroxysms of outrage. Mr. Trump’s decision on Wednesday to, as he proclaimed on Twitter, sign an “Executive Order prohibiting immigration into our Country today” seems designed as just such a distraction.

The president first announced his intention in a late-night tweet on Monday, claiming it was a necessary response to “the attack from the Invisible Enemy” — his latest nickname for the coronavirus — and “to protect the jobs of our GREAT American citizens.” Like clockwork, Democrats denounced his “xenophobia” and accused him of trying to shift the nation’s focus away from his handling of the pandemic.

But the outcry is also behind the curve. In the name of protecting the nation, the Trump administration has already shut down most legal immigration through more piecemeal moves. In recent weeks, it has imposed tougher travel restrictions and has stopped processing most visas. Visa interviews are not taking place, nor are citizenship ceremonies. Migrants crossing the border are now turned back without the usual protections for minors and asylum seekers.

As Mr. Trump elaborated at his Tuesday news briefing, there will be a 60-day “pause” in issuing new green cards — though he said that could be extended “based on economic conditions.” Responding in part to a backlash from business, the ban, for now at least, will not affect guest worker programs, including seasonal farm workers and individuals with H-1B visas.