A group of U.S. tactical reconnaissance aircraft of the U.S. Forces Korea returned to their home base in Pyeongtaek, Gyeonggi Province on Thursday after spending an unusually long 40 days in Japan.

The U-2 spy planes often fly to Japan when they train with the U.S. Forces Japan, but this time they spent more than 40 days there even though they did not participate in any drills.

"Four U-2s returned to Osan Air Base today after being temporarily deployed at Kadena Air Base in Okinawa since Jan. 23," a government official here said Thursday. "They collected intelligence about North Korea from there while participating in the U.S. military's intelligence activities across East Asia."

Their main job, however, is monitoring and taking pictures of various targets in the North from an altitude of 15,000 m.

