"No object entered orbit and no debris fell on Japan."
US military authorities "assessed the space launch vehicle as not a threat to North America or Hawaii and took no action in response to this launch", the statement added.
Earlier, state media in North Korea said that the "Kwangmyongsong-2" satellite had been placed in orbit.
The satellite was transmitting data and the "Song of General Kim Il-sung" and "Song of General Kim Jong-il" - references to the late founder of North Korea and his son, the current leader - the report said.
The BBC's John Sudworth in Seoul says a failure would seriously detract from North Korea's ability to exploit the propaganda value of the launch, although it may never admit it to its own people.
In a previous satellite launch attempt in 1998, North Korea said it was sending up a device that would orbit the world transmitting revolutionary melodies.
It claimed this was also successful but the launch is believed to have been a failure as no trace of the satellite was ever found.
North Korea gave prior warning of the launch and repeatedly said it was using it as part of the peaceful pursuit of a space programme, as is its right under international law.
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