President Trump on Wednesday, April 24, said Mexico needs to do more to prevent illegal immigrants from reaching the U.S .- Mexico border, and threatened using armed soldiers and closing the border.

“A very big Caravan of over 20,000 people started up through Mexico. It has been reduced in size by Mexico but is still coming. Mexico must apprehend the remainder or we will be forced to close that section of the Border & call up the Military. The Coyotes & Cartels have weapons,” the president tweeted.

Mexico’s Interior Secretary Olga Sanchez Cordero predicted that by March 29, about 20,000 migrants would be part of the caravan, days after the caravan had formed, according to Washington Examiner.

Sanchez called the migrant group “caravan madre,” prompting those in American media to call it “mother of all caravans.” The caravan is expected to arrive later this week in Mexico City, according to local media reports.

President Trump continued later: “Mexico’s Soldiers recently pulled guns on our National Guard Soldiers, probably as a diversionary tactic for drug smugglers on the Border. Better not happen again! We are now sending ARMED SOLDIERS to the Border. Mexico is not doing nearly enough in apprehending & returning.” 

The caravan reportedly includes members from Central America, along with people from Cuba, Haiti, and Africa.

President Trump tweeted last Wednesday that Democrats need to go back to Washington to fix the border and immigration crisis.

“Democrats in Congress must return from their Vacations and change the Immigration Laws, or the Border, despite the great job being done by Border Patrol, will only get worse. Big sections of Wall now being built,” the president tweeted.