U.S. military programs and national security concerns have come under fresh scrutiny in the wake of last week’s deadly shooting at Naval Air Station Pensacola in Florida.

The attack, which claimed the lives of three people and injured eight more, has been classified by federal investigators as “an act of terrorism” after a member of the Saudi Arabian military, Mohammed Alshamrani, 21, was identified as the perpetrator.

“In light of the shooting, it is clear that the vetting process for foreign military students to study in the United States is insufficient,” Gilberto Villahermosa, a retired U.S. Army colonel and national security analyst, told Fox News. “We rely on our foreign partners – in this case, Saudi Arabia – to do the bulk of the work when it comes to vetting these students. We also rely on them to share the results. Some countries have a more rigorous vetting process than others. Although theoretically, only the best and brightest should be chosen, often, the selection is based on family connections and politics.”

Alshamrani – who was killed by law enforcement responding to the attack – embarked on his three-year curriculum in August 2017, starting with language training followed by basic aviation and initial pilot training, a Pentagon official told Fox News. He was slated to finish in 2020.

However, little is known about his whereabouts and movements during much of this year, other than his filing of a formal complaint in April after an instructor referred to as “Porn Stash.” He also visited New York City with other foreigners, according to The New York Times.

Pentagon officials said that Alshamrani returned to Saudi Arabia on breaks and last returned to the U.S. in February 2019. Yet he only checked into his new training unit at the Pensacola base a few days prior to the attack, raising questions over the monitoring procedures and how his months in the United States were spent.

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An Air Force carry team moves the transfer case containing the remains of Navy Seaman Apprentice Cameron Scott Walters, of Richmond Hill, Ga., Sunday, Dec. 8, 2019, at Dover Air Force Base, Del. A Saudi gunman killed three people including Walters in a shooting at Naval Air Station Pensacola in Florida. (AP)

A Department of Defense source told Fox News that the lapse seemingly stemmed from Alshamrani starting the program with a language school at another base. A lot of times flight school is backed up, so it is not unique to have to wait months before starting with a new class.

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According to Pentagon figures, there are 852 Saudis currently in the U.S. undergoing training paid for by the Kingdom of Saudi Arabia. The DoD also stated that a total of 5,181 foreigners from 153 different countries are in the U.S. for “security cooperation training.”

Over the past decade, the U.S. Department of State has issued more than 980,000 nonimmigrant visas to Saudi nationals, with Israel the only Middle East country to have been issued more. Pensacola is one of 150 schools were foreigners who undergo training in the U.S.

Air Force Door Attendant Staff Sgt. Siannie Conception closes the door of the transfer vehicle carrying the transfer cases containing the remains of Ensign Cameron Joshua Kaleb Watson, Seaman Mohammed Sameh Haitham, and Seaman Apprentice Cameron Scott Walters, Sunday, Dec. 8, 2019, at Dover Air Force Base, Del. A Saudi gunman killed the three people in a shooting at Naval Air Station Pensacola in Florida. (AP)

The attack on Dec. 6 has prompted questions with regard to the security vetting process, igniting a mixed response as to its effectiveness.

“It is rigorous but depends on the competence of both the local security services and the Embassy. The armed forces of the foreign country receiving training nominate candidates for training,” said Lt. Gen. Tom Spoehr, Director of Heritage’s Center for National Defense. “Once a foreign military has nominated a candidate, it is the responsibility of the ambassador to perform the security vetting process, in concert with local authorities and the local armed forces.”

A Pentagon official told Fox News that the U.S. Department of State is responsible for the vetting and security clearance process for foreign nationals. Once approved, they enter on a student training visa.

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“If students have made no visible statements or have no past of extremism, unfortunately there is not much that can be done,” noted Michael Noonan, Director of the Program on National Security at the Foreign Policy Research Institute.

The International Military Education and Training (IMET) program, which is managed by both the U.S. Department of State and the Defense Security Cooperation Agency, is designed to accommodate personnel from “allied and friendly nations.” It grants financial assistance to "selected foreign military and civilian personnel for training and education on U.S. military practices and standards, including democratic values,” according to the Congressional Research Service.

The main gate at Naval Air Station Pensacola on Navy Boulevard in Pensacola. (U.S. Navy photo)

Training ranges from English language and flight training to on-the-job and professional military education. Since the end of World War ll, the Pentagon has adopted cooperation programs as a means to boost military relationships and responsible U.S. arms sales.

“When a country selects a person for training, it is because this individual achieved a high degree of competence and made it through a rigorous selection process. The host country vets these individuals before their names are submitted to the U.S. for further background checks,” explained retired Air Force Lt. Col. Rudolph Atallah, now chief executive officer of White Mountain Research, and former Africa Counterterrorism in the Office of the Secretary of Defense.

“The Saudi programs have been around for many years; most of the students have connections to the Saudi Royal family. Once they are vetted and accepted, the system gives them the freedom to explore U.S. culture while attending military schools. They are not put on a short leash.”

Last week’s tragedy is not the first problem to have plagued the decades-old initiative.

The NAS Pensacola shooter is identified as Mohammed Alshamrani, a 21-year-old 2nd Lieutenant in the Royal Saudi Air Force who was a student naval flight officer of Naval Aviation Schools Command. (FBI)

In May, the Pentagon was forced to pull the plug on a training program for Afghan pilots in Texas after a government watchdog discovered that some 40 percent of the students were reported as absent without leave. Between 2005 and 2017, over 2,500 Afghan military trainees were brought to the United States – and a reported 152 went missing, the watchdog reported in 2017. More than 38 were arrested on immigration violations, such as “not reporting for the training for which the visa was issued.”

Nonetheless, the Special Inspector General for Afghanistan Reconstruction (SIGAR) has pointed out that Afghans only account for half the foreign military trainees to go AWOL – the term for going missing without leave – since 2005, with the remainder hailing from a number of different countries. The AWOL issue was first brought to public light in 2010, yet the program continued with defections through this year. A similar program in Georgia is also now facing the chopping block next year amid high desertion rates.

“When I was training at Fort Knox in the 1990s, we had a Saudi officer in my class, and he would go to (prayer) services on Friday with little or no warning. Otherwise, there would be accountability formations that would track attendance for classes,” Noonan recalled. “I assume there will be a crackdown after this event.”

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Moreover, concerns have also been raised that students may use advanced training to oppress or commit human rights abuses after returning home; other experts have conjectured.

“In all human endeavors, you will have bad eggs. Normally these come to the attention of the faculty relatively quickly, and they are told to shape up or are sent home quickly,” Spoehr said. “Given that this is the first incident in recent memory, it does not suggest there is a trend.”

But others in the national security sphere believe the Pensacola shooting should be a wake-up call.

“It is clear we face a new security concern and that we need to re-examine our procedures,” Villahermosa said. “Congress needs to call for a full report on the number of foreign military students studying in the United States, which should include all incidents and cases where foreign students violated security procedures, threatened others, committed crimes, and were sent back to their home countries.”

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Sen. Rick Scott, R-Fla., has called for a “full review of the U.S. military programs to train foreign nationals,” while the area’s representative Matt Gaetz has advocated for “extreme vetting” of foreigners who intend to enter the U.S. for training. Moreover, Rep. Michael Waltz of Florida, a retired Green Beret, noted on twitter that someone “dropped the ball” in regard to Alshamrani’s screening process.

Secretary of Defense Mark Esper said on Fox News Sunday that the Pentagon plans to review the screening of foreign officers who train at U.S. bases while stressing the importance of maintaining the partnerships. Indeed, those involved in the programs have also highlighted their importance and their value for national security purposes.

“When foreign countries purchase military equipment from the U.S., they aren’t just purchasing the equipment. It’s a whole package deal, and with that, they get to be part of our training programs,” said Ethan Jago, a U.S. Airforce veteran formerly involved in training foreign nationals. “You can’t just shut these things down. The training and tactics we share are for the betterment of our world security. We need to train allies so that we don’t have to send our troops over when (problems) arise.”

Investigators so far are endeavoring to determine whether Alshamrani acted alone. Regardless, global terrorist groups have been quick to praise his brazen attack as a source of inspiration.

Authorities over the weekend affirmed that in the days prior to the shooting, Alshamrani hosted a dinner party where he and three others watched videos of mass shootings. Moreover, an unverified – and since suspended – social media account presumably linked to the attacker posted anti-American and anti-Israeli messages prior to the onslaught.

The White House confirmed Sunday that President Trump had spoken with Crown Prince Mohammad Bin Salman, who reiterated Saudi Arabia’s commitment to “working with the United States to prevent a horrific attack from ever happening again.”

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Investigators are additionally probing whether students who recorded the barrage outside a classroom building did so as part of a plot, or if it was merely an opportune moment.

“Investigators have recovered digital evidence as part of this investigation. This includes multiple videos from base security surveillance, as well as cell phone videos that were taken by a bystander from outside the building after the attack had started and after first responders had arrived,” said Marc Raimondi, National Security Spokesman at the U.S. Department of Justice. “We have interviewed that person, and are analyzing the videos to determine if any details can further this investigation. To confirm, we are not aware of any credible threat to the community at this time.”

The U.S. State Department did not respond to a request for comment.

Lucas Tomlinson contributed to this report.