Mitsubishi Heavy Industries Ltd. and the Japan Aerospace Exploration Agency said one of the satellites, equipped with radar, is capable of identifying objects just one meter across even in bad weather and at night, the Yomiuri Shimbun reported.
In combination with two optical sensor satellites and another radar satellite already in orbit, this satellite will make it possible to observe any spot on Earth once a day, officials said.
Japan has significantly stepped up it surveillance satellite capabilities following ballistic missile test launches conducted by North Korea, the latest one in December.
A demonstration satellite with a high-resolution optical system for engineering test purposes was also launched Sunday, with the two satellites being put into a polar orbit circling Earth south to north, they said.
Equipped with a powerful telescopic lens, the optical satellite is reported to have a discrimination capability equal to that of U.S. private-sector spy satellites that can identify objects on Earth about 15 inches in diameter during clear weather.
The two satellites were launched under the authority of the Cabinet Satellite Intelligence Center, operating with a budget appropriation for fiscal 2012 of around $10.1 billion.