Writing on Twitter Monday morning, Trump explained that because Guatemala, Honduras, and El Salvador “were not able to do the job of stopping people from leaving their country and coming illegally to the U.S.,” the administration will “cut off” or “substantially reduce” the aid provided to these countries.

Guatemala, Honduras and El Salvador were not able to do the job of stopping people from leaving their country and coming illegally to the U.S. We will now begin cutting off, or substantially reducing, the massive foreign aid routinely given to them.

— Donald J. Trump (@realDonaldTrump) October 22, 2018

Furthermore, claiming that “criminals and unknown Middle Easterners are mixed in,” Trump called the caravan a national emergency and tweeted that he has alerted border patrol and the military. “Must change laws!” he added.

In a third tweet, he blamed Democrats for “not giving us the votes to change our pathetic Immigration Laws! Remember the Midterms! So unfair to those who come in legally.”

Trump had earlier called on Mexico to stop “this onslaught” before it reached the U.S. border, and threatened to “call up the U.S. Military and CLOSE OUR SOUTHERN BORDER” if Mexico failed to do so.

Since taking office, Trump has already planned to significantly reduce aid to Guatemala, Honduras, and El Salvador. According to data reported by Reuters, aid to the three countries is due to drop by nearly 40% between 2016 and next year, from a total of approximately $297 million to $181 million. It’s unclear what Trump plans to do in order to alter U.S. aid given to these Central American countries, as Congress is not scheduled to be back in session until after the election.

The caravan, which reportedly carried just 200 people when it first formed, has swelled to as many as 7,000. By Monday morning, the caravan was moving through the Mexican city of Tapachula.