(CNN) More than a dozen Saudi servicemen training at US military installations will be expelled from the United States after a review that followed the deadly shooting last month at a Naval Air Station in Pensacola, Florida, multiple sources told CNN.

The Saudis are not accused of aiding the 21-year-old Saudi Air Force second lieutenant who killed three American sailors in the December shooting, two sources said, but some are said to have connections to extremist movements, according to a person familiar with the situation.

A number are also accused of possessing child pornography, according to a defense official and the person familiar with the situation. The FBI and Justice Department declined to comment.

"In the wake of the Pensacola tragedy, the Department of Defense restricted to classroom training programs foreign military students from Saudi Arabia while we conducted a review and enhancement of our foreign student vetting procedures," said Lt. Col. Robert Carver, a spokesman for the Department of Defense. "That training pause is still in place while we implement new screening and security measures."

About a dozen Saudi trainees at the Pensacola base had been confined to their quarters as the FBI investigated the shooting as a potential terror attack, and the Pentagon initiated a review of all Saudi military trainees in the country, numbering around 850 students.

Read More