The central government is considering regulating the use of drones above U.S. military facilities in the country, following a request by U.S. forces overseeing the Asia-Pacific region, a government source said Wednesday.

Japan has a law that bans drones from being flown over key facilities such as the Prime Minister’s Office and the Imperial Palace in Tokyo. But U.S. military facilities are not explicitly mentioned as restricted areas, according to the transport ministry.

The Defense Ministry said drones flown above the U.S. military’s Camp Schwab on the southern island of Okinawa could get in the way of helicopters also flying in the area. The drones could also be used for terror attacks, posing a security threat.

“It’s the Japanese government’s responsibility to ensure the safety of the U.S. military. We must consider necessary steps (to address the problem),” a senior ministry official said.

Adm. Harry Harris, who leads U.S. Pacific Command, directly urged Japanese Defense Minister Itsunori Onodera to set the drone regulations during their talks in Tokyo on Nov. 16, according to the source.

Some 50,000 U.S. troops are stationed in Japan. U.S. forces are dispersed among roughly 80 facilities nationwide, the bulk of which are in Okinawa Prefecture.