WASHINGTON (AP) — Abandoning his threat to immediately seal the southern border, President Donald Trump warned instead that he'd slap tariffs on cars coming to the U.S. from Mexico unless the Mexicans do more to stop the flow of migrants and drugs to the U.S.

In his latest backtrack in recent days, Trump told reporters Thursday he would try the "less drastic measure" before resorting to his standing border-closure threat.

"Mexico understands that we're going to close the border or I'm going to tariff the cars. I'll do one or the other. And probably start off with the tariffs," Trump said. He added later: "I don't think we'll ever have to close the border because the penalty of tariffs on cars coming into the United States from Mexico, at 25 percent, will be massive."

It was the latest, seemingly sudden attempt at new leverage by a president struggling to solve what his administration has called a border "crisis." And it was a dramatic departure for Trump, who last week tweeted that he would close the border or large swaths of it this week unless Mexico immediately halted "ALL illegal immigration coming into the United States" — a seemingly impossible task.

Trump said at the time that he was "not kidding around," and his acting chief of staff Mick Mulvaney said in a television interview Sunday that it would take "something dramatic" for Trump not to close down the crossings.