WASHINGTON — President Donald Trump said Friday that next week he would close the southern border, or at least large sections of it, if Mexico does not halt illegal immigration into the United States, repeating a threat he has made before but never with a specific timetable.

In a series of tweets and later during an appearance before reporters, Trump did not spell out exactly what a border closing would entail but said it could involve halting ‘‘all trade’’ between the two countries - a prospect that would have profound ramifications for the US economy.

Trump blamed Mexico for a growing flow of ‘‘illegals’’ entering the United States and cited two large migrant caravans making their way toward the US border.


‘‘If they don’t stop them, we’re closing the border,’’ Trump said at an event in Florida. ‘‘We’ll close it. And we’ll keep it closed for a long time. I’m not playing games. Mexico has to stop it.’’

His warning echoed tweets earlier in the day in which Trump threatened that he would be ‘‘CLOSING the Border, or large sections of the Border’’ if the situation did not improve.

Trump’s comments came two days after the nation’s top border official warned that the U.S. immigration enforcement system along the nation’s southern boundary is at ‘‘the breaking point’’ and said authorities are having to release migrants into the country after background checks because of a crush of asylum-seeking families with children.

Kevin McAleenan, the commissioner of US Customs and Border Protection, said that for the first time in more than a decade, his agency is ‘‘reluctantly’’ performing direct releases of migrants, meaning they are not turned over to Immigration and Customs Enforcement, they are not detained, they are not given ankle bracelets to track their movements, and they are allowed to leave with just a notice to appear in court at a later date.


A move to close the border would come with numerous complications, including impeding US citizens seeking to reenter the country from Mexico.

Closing off access to foreigners with travel visas would invite the same kind of legal scrutiny as Trump’s ban on people coming into the United States from certain Muslim-majority countries.

And if Trump shut down commerce between Mexico and the United States, he would draw the ire of American manufacturers who depend on Mexican-made goods.

Trump made a similar threat Thursday morning about closing the border, saying Mexico was ‘‘all talk and no action,’’ but did not make it sound as though action was imminent. ‘‘May close the Southern Border!’’ he wrote then.

At a rally in Grand Rapids, Michigan, on Thursday night, Trump returned to the subject, saying if Mexico does not stop migrants from trying to enter the United States, ‘‘we will close the damn border.’’

Trump alleged Mexico was stealing the state’s car business and told the crowd that if he closes the border then ‘‘it means you’re going to make more cars right here in the good old USA.’’

Trump has threatened to close the border before but did not follow through.

In November, in the heat of a battle with Congress over funding for his long-promised border wall, Trump wrote on Twitter ‘‘we will close the Border permanently if need be.’’

Trump has since declared a national emergency at the border as a way to spend more on barriers than Congress has authorized.


In his tweets Friday, Trump also took aim at Democrats in Congress, saying they ‘‘have given us the weakest immigration laws anywhere in the World.’’