President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE claimed on Tuesday that a border wall is necessary to prevent a "tremendous medical problem" tied to immigration.

"One of the problems that people don't talk about, you have a tremendous medical problem coming into our country," he said during a bill signing ceremony. "Tremendous problems. People don't want to talk about it."

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There is no available evidence suggesting immigrants have caused any modern disease outbreaks in the U.S. The vast majority of immigrants entering the country are required to be screened for medical conditions by the Centers for Disease Control and Prevention under the Immigration and Nationality Act.

Trump linked immigrants to diseases earlier in the day when he met with House Minority Leader Nancy Pelosi (D-Calif.) and Senate Minority Leader Charles Schumer (D-N.Y.) in the Oval Office.

"People with tremendous medial problems are pouring into our country," he said during the televised portion of that meeting.

On Tuesday morning he tweeted that open borders bring "large scale crime and disease."

On the campaign trail, Trump once said that "tremendous infectious disease is pouring across the border. The United States has become a dumping ground for Mexico and, in fact, for many other parts of the world."

During Tuesday's bill signing Trump also doubled down on his pledge to shut down the government over border funding, while noting characterizing his meeting with Pelosi and Schumer as being "very good" after the TV cameras were no longer in the room.

"I thought it was a very good meeting... when the press left we had a fairly long meeting and we really discussed a lot of great subjects," he said. "I don’t mind ... closing down the country over border security."

Updated at 5:04 p.m.