(CNN) President Donald Trump threatened Friday to cut off aid to countries that allow drugs into the United States during a visit to the Customs and Border Protection National Training Center in Virginia.

"I want to stop the aid. If they can't stop drugs from coming in, 'cause they can stop them a lot easier than us. They say, 'oh we can't control it.' Oh great, we're supposed to control it," the President said. "So we give them billions and billions of dollars, and they don't do what they're supposed to be doing, and they know that. But we're going to take a very harsh action."

Trump specifically name-checked El Salvador, Guatemala, Honduras and Mexico in his criticism of countries whose citizens are coming into the United States illegally.

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"We want strong borders. We want to give you laws. We want to stop the catch and release nonsense that goes on. You catch somebody and you release them. You know they're bad," he said. "They're pouring in from El Salvador, Guatemala, Honduras, Mexico, all over. They're just pouring into our country."

The President added: "These countries are not our friends, you know."

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