WASHINGTON, DC, USA (AP) — President Donald Trump yesterday threatened to close the nation’s Mexican border or large sections of it next week, a potentially drastic step affecting both nations’ economies, if Mexico does not halt illegal immigration at once.

“It could mean all trade with Mexico,” Trump said when questioned by reporters in Florida. “We will close it for a long time. I am not kidding around.”

Trump has previously threatened to close the border — including at a rally in Grand Rapids, Michigan, Thursday night — but this time was different as he gave a timetable. The White House did not immediately respond to questions about whether his possible action would apply to commercial and air travel, but a substantial closure could have an especially heavy impact on both nations.

“If Mexico doesn’t immediately stop ALL illegal immigration coming into the United States through our Southern Border, I will be CLOSING the Border, or large sections of the Border, next week,” Trump said in a tweet. “This would be so easy for Mexico to do, but they just take our money and ‘talk’.”

A senior Homeland Security official suggested Trump was referring to the ongoing surge of mostly Central American families crossing the border from Mexico, though many of those families request asylum under US law.

Those seeking asylum are not deemed illegal simply by their arrival.

The official said the US might close designated ports of entry to re-deploy staff to help process parents and children.

Ports of entry are official crossing points that are used by residents and commercial vehicles. The official, who spoke to reporters on condition of anonymity, did not specify which ports the administration was considering closing, but said only that closures were “on the table”.

Democratic and Republican lawmakers have fought over whether there actually is a “crisis” at the border, particularly amid Trump’s push for a border wall which he claims will solve immigration problems. Wisconsin Republican Senator Ron Johnson, chairman of the Senate Homeland Security Committee, said Thursday the immigration system is cracking under the strain.

The president called on Congress to immediately change what he said were weak US immigration laws, which he blamed on Democrats.