IN BETWEEN TWEETS complaining about Fox News polling numbers and boasting about the size of future rallies, President Donald Trump took a moment on Monday to send shock waves through immigrant communities with a threat meant to rally his base — but one that is not actually logistically possible.

“Next week ICE will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States,” he tweeted. “They will be removed as fast as they come in.” An administration official later told the Associated Press that the effort would target people who have received final orders of deportation. There are more than 1 million people living in the United States with final deportation orders, among an undocumented population of about 11 million.