ARI SHAPIRO, HOST:
Immigration and security experts are raising questions about Donald Trump's call for enhanced screening of immigrants to the United States. On Monday the Republican presidential nominee proposed a new ideological test for immigrants as a way to screen out would-be terrorists.
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DONALD TRUMP: I call it extreme, extreme vetting. Our country has enough problems. We don't need more.
SHAPIRO: So far the Trump campaign has offered few details of how the candidate's plan would work in practice. NPR's Scott Horsley reports.
SCOTT HORSLEY, BYLINE: Donald Trump says immigrants or the children of immigrants are to blame for a string of recent terror attacks in the U.S. He's proposing more scrutiny of people trying to enter the country to weed out those who support bigotry or hatred.
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TRUMP: Only those who we expect to flourish in our country and to embrace a tolerant American society should be issued visas.
HORSLEY: Visa applicants are already fingerprinted and checked against various terrorist databases. But former Homeland Security official Joseph King says it's harder to screen out people with hostile attitudes who have yet to act on them.
JOSEPH KING: ISIS doesn't hand out membership cards. If I'm an evil-doer, I'll just lie. Unless you strap me to a polygraph, I don't know how you get around that.
HORSLEY: The Trump campaign did not respond to questions about who'd be subject to the extreme vetting or what form it might take. In the past, the U.S. has screened out would-be immigrants who belonged to overseas communist parties or who advocated the violent overthrow of the U.S. government. But Doris Meissner, who led the immigration service in the 1990s, says that kind of ideological test is not easy to apply.
DORIS MEISSNER: That exclusion is still in the immigration statutes, but it's been diluted heavily over the years largely because it was impractical to implement.
HORSLEY: But Mark Krikorian, who heads the Center for Immigration Studies, thinks Trump's proposal is overdue. He says there's value in asking visitors if they support ideals such as tolerance and religious liberty. And he likes Trump's idea of interviewing friends and relatives of would-be immigrants and checking their social media trail.
MARK KRIKORIAN: Look at their Facebook pages basically, and do they have pages saying, you know, Allahu Akbar and death to Great Satan and all that?
HORSLEY: After last year's San Bernardino massacre, FBI agents found evidence one of the shooters had sent private messages via Facebook to friends in Pakistan in which he expressed support for Islamic jihad. Tracing such digital footprints ahead of time would take an enormous investment of resources, though. The U.S. grants permanent residency to over a million visitors each year.
KRIKORIAN: The bigger the haystack, the harder it is to find the needle.
HORSLEY: Krikorian's group advocates a reduction in the number of immigrants allowed in the U.S. In his speech this week, Trump agreed cuts would be necessary to carry out the kind of scrutiny he wants.
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TRUMP: If we don't control the numbers, we can't perform adequate screening. There is no way it can take place.
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HORSLEY: A survey this spring by the Pew Research Center found nearly 7 out of 10 Trump backers considered immigrants a net drain on society. The public in general has a more favorable view of immigrants, though. Doris Meissner, who is now with the Migration Policy Institute in Washington, thinks many Americans will look skeptically at Trump's extreme vetting proposal.
MEISSNER: Well, it would be very, very disruptive, and there would be a tremendous amount of pushback from the business community, from institutions of higher education, from American families.
HORSLEY: Other countries might retaliate with tougher screening of their own, posing a challenge for Americans when they try to travel abroad. Scott Horsley, NPR News, Washington. Transcript provided by NPR, Copyright NPR.
