President Donald Trump reminded critics of his tough immigration policy on Monday that criminals were using children to cross the Southern border.

“Children are being used by some of the worst criminals on earth as a means to enter our country,” Trump wrote on Twitter.

The president pointed to increased crime rates in countries south of the United States, warning that accepting more illegal immigrants would bring more violent crime into the United States.

“Has anyone been looking at the Crime taking place south of the border,” he wrote. “It is historic, with some countries the most dangerous places in the world. Not going to happen in the U.S.”

Trump blamed Democrats for failing to support tougher immigration laws to stop illegal immigration.

“CHANGE THE LAWS!” he wrote in all-caps. “It is the Democrats fault for being weak and ineffective with Boarder Security and Crime. Tell them to start thinking about the people devastated by Crime coming from illegal immigration.”

Children are being used by some of the worst criminals on earth as a means to enter our country. Has anyone been looking at the Crime taking place south of the border. It is historic, with some countries the most dangerous places in the world. Not going to happen in the U.S. — Donald J. Trump (@realDonaldTrump) June 18, 2018

CHANGE THE LAWS! — Donald J. Trump (@realDonaldTrump) June 18, 2018