Are thousands of Islamic terrorists entering the United States?

Question

In an interview with an Ohio television station, the 2016 Republican nominee for President said:

when you have radical Islamic terrorists probably all over the place, we’re allowing them to come in [to the United States] by the thousands and thousands.

Later in the same interview:

“And, you know, I’m not going to change my views on that. We have radical Islamic terrorists coming in that have to be stopped. We’re taking them in by the thousands.”

Relatives of mine have expressed the same idea to me. Are thousands and thousands of Islamic terrorists entering the United States?

Answer 1

This is a claim that he has used multiple times and there has been no evidence to support his claim. As the article notes, "Trump is in the numerical ballpark if he’s referring to the number of refugees being admitted into the United States every year" but it would be wrong to suggest that these immigrants are all terrorists.

Trump seems to be referring to terrorists and violent extremists. But there is no evidence that tens of thousands of terrorists are being admitted into the United States today -- much less that they are being "allowed" in, as if there is a visa preference program for terrorists.

On the other hand, Trump is in the numerical ballpark if he’s referring to the number of refugees being admitted into the United States every year -- something else he’s expressed reservations about.

Answer 2

I'm not sure to what group of people he is referring - normal Muslim immigrants from non-war zones just relocating to the US? Refugees?

If he is referring to refugees, this is unlikely, as these are screened extensively before admitted to the US:

FACT: All refugees of all nationalities considered for admission to the United States are subject to the highest level of security checks of any category of traveler to our country, involving multiple federal intelligence, security and law enforcement agencies, such as the National Counterterrorism Center, the Federal Bureau of Investigation, and the Departments of Homeland Security, State and Defense, in order to ensure that those admitted are not known to pose a threat to our country. The safeguards include biometric (fingerprint) and biographic checks, and an interview by specially trained DHS officers who scrutinize the applicant’s explanation of individual circumstances to ensure the applicant is a bona fide refugee . Mindful of the particular conditions of the Syria crisis, Syrian refugees go through an enhanced level of review.

Therefore only a small number of admitted refugees have any ties to terrorism:

A State Department spokesperson said of the nearly 785,000 refugees admitted through the U.S. Refugee Admissions Program since 9/11, “only about a dozen — a tiny fraction of one percent of admitted refugees — have been arrested or removed from the U.S. due to terrorism concerns that existed prior to their resettlement in the U.S. None of them were Syrian.”

If he's referring to normal, non-refugee immigration, this becomes harder to analyze for a layman - but in my opinion it's worth bearing in mind that only a small (6% from 1980-2005) fraction of terror attacks are carried out by Muslims (the FBI data is slightly outdated, but less comprehensive, more recent data from the New America Think tank suggests the same - 9 Jihadist attacks vs. 18 by right wingers (due to the one large recent outlier, the Jihadist attacks have killed many more though, which, in my opinion, does not change the point.)

Data from the EU suggests that the low percentage of Islamic terrorism is not limited to the US, and instead applies to the Western world in general- if you look at the numbers from the linked Europol report, in 2015, only 17 out of 211 attacks in the EU were carried out by Islamic terrorists. All suggests to me that the 'Muslim terrorist' phenomenon is disproportionately overplayed in the media and by politicians, and therefore this statement is likely to be completely false.

As a further indicator, to back up JasonR's comment about Trump's rather pragmatic relationship with the truth, apparently only 9% of his statements are factually true.

Answer 3

Politifact: Pants on Fire

http://www.politifact.com/truth-o-meter/statements/2016/may/25/donald-trump/donald-trump-says-us-letting-tens-thousands-terror/

"Trump is certainly wrong on the facts here," said Daveed Gartenstein-Ross, a senior fellow at the Foundation for Defense of Democracies. That said, Gartenstein-Ross added that more reasonable concerns could have been expressed with less "hyperbolic" rhetoric.

The recent migrant flows from Syria and Iraq into Europe, he said, have provided greater cover for terrorists than experts had predicted early on, and while the United States is not facing as much risk from its ongoing inflow of refugees, that risk is not zero. Just going by the math, some small fraction of refugees can be expected to either be well-concealed operatives who made it through the screening process or, much more likely, people who self-radicalize after arriving in the United States.

Still, Gartenstein-Ross agreed that there is no evidence that "tens of thousands of them" are already here, as Trump said.

Answer 4

In order to be a terrorist, a person must have committed an act of terrorism.

Since 2000, there have been 14,000 terrorist events committed. Assuming 10 terrorists per event, that leaves 140,000 potential terrorists in the world.

Lets assume that it is actually half of this in terms of unique people, as several terrorists will commit multiple terrorism crimes. Lets also assume that half of these people are dead or imprisoned.

That means there are 35,000 in the world.

Broadly speaking, we could roughly assume that being as 'the west' has seen <1% of those attacks, it contains 1% of the terrorists, that is to say 350. The USA is roughly a quarter of the population of the west, although certain regions such as France are currently a more significant target. Lets say that means 50 terrorists who have entered the US.

The technical minimum number required for thousands and thousands is 4,000, although I think rounding it to 5,000 is needed before the phrase really becomes legitimate to use.

The unnamed Republican Nominee is out by two orders of magnitude.

Apologies for the terrible source:

http://www.dailymail.co.uk/news/article-3322308/Number-people-killed-terrorists-worldwide-soars-80-just-year.html