North Korea launched what appeared to be an intermediate-range missile on Wednesday to a high altitude in the direction of Japan before it plunged into the sea, military officials said, a technological advance for the isolated state after several test failures.
The launch came about two hours after a similar test failed, South Korea's military said, and covered 400 km (250 miles), more than halfway towards the southwest coast of Japan's main island of Honshu.
The launches and earlier nuclear tests show continued defiance of international warnings and a series of U.N. Security Council resolutions and sanctions, which North Korea rejects as an infringement of its sovereignty.
Japanese Defence Minister Gen Nakatani said the second missile reached an altitude of 1,000 km (620 miles), indicating North Korea had made progress.
"We don't know whether it counts as a success, but North Korea has shown some capability with IRBMs (intermediate range ballistic missiles)," he told reporters in Tokyo.
"The threat to Japan is intensifying."