A Pentagon official says he can't comment on a lawsuit filed by three large U.S. cities that says the military failed to properly use the national background check system for guns.

New York City, San Francisco and Philadelphia filed the lawsuit Tuesday in Virginia. The cities argue the Defense Department failed to report "significant numbers" of disqualifying records to the FBI's national background check system for gun licensing and sales. That failure allowed a disgraced former Air Force member to buy a rifle and shoot 26 people to death Nov. 5 in a Texas church.

Pentagon spokesman Tom Crosson says the department is continuing to work with the U.S. military leaders to refine their policies.

Local law enforcement officials rely on the FBI's database to conduct background checks on gun permit applications and to monitor purchases. The lawsuit says it must be up to date.