Washington -- The Trump administration on Tuesday halted immigration applications submitted by nationals from 19 countries that already faced restrictions on travel to the United States, according to a U.S. Citizenship and Immigration Services memo.

"USCIS has considered that this direction may result in delay to the adjudication of some pending applications and has weighed that consequence against the urgent need for the agency to ensure that applicants are vetted and screened to the maximum degree possible," the agency said in a four-page policy memo.

"Ultimately, USCIS has determined that the burden of processing delays that will fall on some applicants is necessary and appropriate in this instance, when weighed against the agency’s obligation to protect and preserve national security," it added.

The New York Times first reported the immigration pause, which applies to both green card and citizenship applicants.

A DHS spokesperson said in a statement that the Trump administration is "making every effort to ensure individuals becoming citizens are the best of the best."

"Citizenship is a privilege, not a right. We will take no chances when the future of our nation is at stake," the spokesperson added.