Liftoff took place at 11:30 a.m. (0230GMT) Sunday from the coastal Musudan-ri launch pad in northeastern North Korea, the South Korean government said. In Washington, the State Department also confirmed the launch.
The rocket flew over Japan and landed in the Pacific Ocean, the Japanese broadcaster NHK said, citing its government.
"Our primary concern is to confirm safety and gather information," Japanese Prime Minister Taro Aso told a news conference at his Tokyo office Sunday.
Resisting calls from President Barack Obama, Aso and Hu Jintao of China to call off the launch, North Korea had announced Saturday that preparations were complete to send communications satellite Kwangmyongsong-2 on a multistage rocket bound for the skies over Japan.
Tokyo deployed warships and Patriot missile interceptors off its northern coast to shoot down any debris that the North said might fall over the area.
US and South Korean warships equipped with missile interceptors also plied the waters between the Korean peninsula and Japan to monitor the launch.
Russia, meanwhile, scrambled fighter jets to its Far East in case any debris hits its territory, Russian news reports said.
North Korea pushed ahead with the launch despite mounting international pressure to cancel a liftoff Obama warned Friday would be a "provocative" act.
South Korea, the US and Japan said earlier in the week they would take North Korea to the UN Security Council for an act they say is banned under a 2006 resolution barring Pyongyang from ballistic activity.
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