WASHINGTON (AP) — The Pentagon says the U.S. has issues a formal complaint to China over the use of lasers near the military base in Djibouti (jih-BOO'-tee) that were directed at aircraft and resulted in minor injuries to two American pilots.

Pentagon spokeswoman Dana White says the U.S. is confident that Chinese nationals are responsible for the use of the lasers. She says the incidents represent a serious threat to U.S. airmen. She says the U.S. has asked China to investigate the incidents.

The Pentagon says reports from pilots indicate that on three occasions the lasers were military grade and came from the Chinese base nearby.

The U.S. has notified airmen to exercise caution when flying in that area. The Chinese recently built a base near Camp Lemonnier, the U.S. base in Djibouti.