Japan Sunday launched another satellite to strengthen its surveillance capabilities, including keeping a closer eye on North Korea as the North vows to stage another nuclear test. The radar-equipped satellite, along with a radar satellite and other optical satellites already in operation, will complete a system first devised in the late 1990s as a response to Pyongyang's 1998 long-range missile launch.The H-IIA rocket blasted off from the southern island of Tanegashima around 1:40 pm (0440 GMT), according to footage on national broadcaster NHK.From an altitude of several hundred kilometres, the satellite will be able to detect objects on the ground as small as a square metre, including at night and through cloud cover.The additional satellite completes a system, albeit almost a decade behind schedule, that allows Japan to monitor any place in the world at least once a day.The rocket also released an experimental optical satellite, whose technology could eventually enhance the monitoring system.The Japan Aerospace Exploration Agency has said the radar satellite would be used for information-gathering, including data following Japan's 2011 quake and tsunami, but did not mention North Korea by name.Pyongyang has vowed to carry out more rocket launches and a third nuclear test in protest at tightened UN sanctions over its banned launches.The North last year launched two long-range rockets. The first failed in April but the second in December flew over the southern Okinawa island chain, jangling nerves in Japan.Tuoitrenews