The Pentagon’s top intelligence official told Congress that since the Naval Air Station Pensacola shooting the Defense Department has been working to screen foreign military students better.

Director for defense intelligence Garry Reid told lawmakers at a Senate Armed Services subcommittee hearing on Wednesday that the Pentagon found it had not taken foreign military students into account as part of its procedures and training on insider threats, according to the Military Times.

“We also found that DOD programs meant to detect and mitigate events such as the Pensacola attack did not cover international military students — for instance, our insider threat programs,” Reid said.

In December, 21-year-old Saudi Air Force 2nd Lt. Mohammed Saeed Alshamrani of Saudi Arabia shot and killed three American sailors and wounded several others at the Florida military base.

After the attack, the Pentagon screened every Saudi student and looked into their social media accounts. Following the two-week investigation, 21 Saudis were expelled for holding extremist views or because they “had contact” with child pornography.

Pentagon officials told lawmakers Wednesday that, going forward, there would be increased efforts to prevent military students with extremist or anti-American views from entering the country. They also said there would be a push to have Saudi Arabia better hold its officers accountable.

While there have been increased vetting measures implemented since the shooting, Lt. Gen. Charles Hooper said that training foreign officers is an important way to cultivate and maintain alliances.

“As a foreign area officer and a career security operator, I have worked alongside many foreign military leaders whose training in the United States established an appreciation for American culture and values and has shaped longstanding cooperation and partnership with the United States,” Hooper told the subcommittee.