President Donald Trump tweeted on Monday morning that the United States would permanently close the southern border if approaching migrants are not apprehended and sent back to their countries.

"Mexico should move the flag waving Migrants, many of whom are stone cold criminals, back to their countries. Do it by plane, do it by bus, do it anyway you want, but they are NOT coming into the U.S.A. We will close the Border permanently if need be," Trump wrote in a tweet. "Congress, fund the WALL!"

Mexico should move the flag waving Migrants, many of whom are stone cold criminals, back to their countries. Do it by plane, do it by bus, do it anyway you want, but they are NOT coming into the U.S.A. We will close the Border permanently if need be. Congress, fund the WALL! — Donald J. Trump (@realDonaldTrump) November 26, 2018

Trump was responding to reports that around 500 migrants stormed the Mexican blockades and rushed toward the U.S. border between Mexico's Tijuana and San Diego to the north. Some migrants threw rocks and other projectiles at border patrol agents, and in response, the agents used tear gas on the crowd.

Department of Homeland Security Secretary Kirstjen Nielsen released a statement confirming some migrants who tried to cross the border had thrown projectiles at border patrol agents.