The United States is poised to expel more than a dozen Saudi servicemen training at U.S. military installations following a review of last month's shooting at the naval air station in Pensacola, Florida.

According to CNN, the trainees are not accused of aiding the shooter, a 21-year-old Saudi Air Force second lieutenant who killed three American sailors and wounded several others, but are said to have connections to extremist movements. Sources told the outlet that some are also accused of possessing child pornography.

Last month, Mohammed Saeed Alshamrani, a Saudi flight student, opened fire at the naval air station before he was killed by responding law enforcement officers.

Since then, about a dozen Saudi trainees at the base have been confined to their quarters while the FBI investigated the shooting as a possible terror attack and the Pentagon reviewed all Saudi military trainees in the country. The Navy also grounded around 300 Saudi military aviation students at three different bases as part of a "safety stand-down."

The Department of Justice is expected to declare that the shooting was an act of terrorism, a U.S. official told CNN. No co-conspirators have been charged.