In a trio of tweets, the president escalated his rhetoric surrounding the group of migrants, declaring a national emergency as they approach the border and claiming that "unknown Middle Easterners" had joined the group.

Trump, in the tweets, did not offer any evidence for the charge that people from the Middle East were among those crossing the border.

"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," Trump wrote in a tweet.

"Sadly, it looks like Mexico's Police and Military are unable to stop the Caravan heading to the Southern Border of the United States. Criminals and unknown Middle Easterners are mixed in. I have alerted Border Patrol and Military that this is a National [Emergency]. Must change laws!"