Over the fifteen year period since the terrorist attacks of 2001, the number of foreign students enrolled in American colleges and universities increased 72 percent.

During this same period, the number of students from Saudi Arabia grew by 1,000 percent and the number from the 19 nations of the Middle East and North Africa more than tripled.

Should we be concerned about the rapidly expanding Muslim foreign student population at our universities? Should we assume that since Saudi Arabia is an ally in the region, its students will be immune to jihadist recruitment? Have we forgotten that a majority of the 9/11 hijackers were Saudis, not Syrians, Sudanese, or Egyptians?

It’s true that among the top ten nations sending foreign students to the U.S., Saudi Arabia ranks only fourth behind China, India and South Korea.

But it ranks number one in the rate of increase in that student population. In the most recent year, the number grew by 11.5 percent from 2014 to 2015. Among Muslim nations, only Turkey saw a decline in 2015 in the number of students sent to the U.S. for graduate and undergraduate study.

So, foreign student study at American colleges is a growth industry and has been since the end of World War II.  Americans are justifiably proud that our universities attract huge numbers of foreign students, and the universities are delighted at the billions in tuition dollars the foreign students bring. The total for the 2014-15 academic year was just short of one million — 974,926. We know the annual numbers courtesy of the U.S. State Department’s annual “Open Door” report, and the number actually exceeds 1,000,000 if we include foreign students admitted to the US on visas other than the F-1.

Foreign students are not spread evenly across 50 states and our 4-year degree granting institutions. They are concentrated in a dozen big cities that are home to major research universities– like New York, Boston, Chicago, Los Angeles and the San Francisco bay area. Thus, even though foreign students are only 4 percent of the total student population at our colleges, they are over 10 percent at many institutions.

How much do we know about our 1.1 million foreign students? How much do we need to know? Is this foreign student population being targeted by Al-Qaeda and ISIS? Is the ocean wet?

It is true that a substantial majority of the 59,945 Saudi students now on F-1 visas are funded by scholarships from Saudi government-sponsored foundations, and presumably those foundations do conduct some kind of screening for overt terrorist affiliations.

However, the Saudi government may not be as diligent in that effort as, say, our FBI might be if given that task. But to date, the FBI has never been tasked with doing routine background checks on foreign students. Understandably, the FBI might be more worried about the 10,000 Syrian refugees Obama wants to bring to the U.S. in 2016 and the 50,000 planned for 2017.

We know the system for vetting foreign students is not going to change under Obama, but if we are honest, we also now it is unlikely to change under a Republican president, and we know the main reason for complacency is commercial. Universities and the corporate sector want nothing to impede the flow of increasing numbers of foreign students. Collectively, they add an estimated $27 billion to our economy annually and are a source of cheap labor as well.

And yet, the issue of infiltration of Islamist radicals into our universities is not a hypothetical question. It is a matter of public record that has already happened.

It would be extremely naive to think they are not a few dozen to be found among the 100,000-plus Muslim students now enjoying “academic pursuits” in Berkeley, Chicago and Los Angeles.

We know that ISIS is actively recruiting among that population. In fact, news reports confirm that ISIS has a high-tech branch that is recruiting scientists, engineers, and computer technicians to plan and deliver devastating terrorist attacks in Europe and America.

What can be done? No one will deny that it is a very good thing that our university programs in science, engineering, medicine and business are attracting over a million foreign students annually. But most Americans will say there needs to be a greater awareness of the infiltration problem and a greater urgency in identifying the defeating jihadist plots among that population.

We can add this to the long list of national security vulnerabilities that have been ignored for too long.