North Korea says a new unit to operate the reconnaissance satellite launched last month began its mission on Saturday.

The ruling Workers' Party newspaper, Rodong Sinmun, said on Sunday the mission had been tasked to the reconnaissance satellite operation office at the Pyongyang General Control Centre of the National Aerospace Technology Administration, or NATA.

The paper said information gathered by the satellite will be offered to "major units" responsible for war deterrence, and to the General Reconnaissance Bureau of the Korean People's Army.

Pyongyang said earlier the satellite had taken images on a trial basis of the White House and the Pentagon, as well as US Kadena Air Base in Japan's southwestern prefecture of Okinawa, and US bases in South Korea and Guam.

North Korea's defense ministry was quoted as saying it expects the country's war deterrence to assume a "more perfect military posture."

Observers say the satellite is part of Pyongyang's efforts to beef up monitoring of moves by Japan, the United States and South Korea.