There has been widespread condemnation of a long-range rocket launch by North Korea, which went ahead in defiance of international warnings.
North Korea said it had succeeded in putting a satellite into orbit - a claim backed by international observers.
The launch is seen by North Korea's enemies as cover for a ballistic missile test.
Japan has requested an urgent meeting of the UN Security Council, and the United States called it a highly provocative act that threatened regional security.
China, North Korea's only ally, expressed regret but said that any UN action should be moderate and avoid escalating tensions.
The BBC's Rupert Wingfield-Hayes said that "this appears to have been a dramatic success for North Korea".
"Even if it were a peaceful programme, this is exactly the same technology that you use for long range missiles," he explained.
John Everard, a former British ambassador to North Korea and now a consultant for the UN, told the Today programme's John Humphrys that "this is a very serious development... it's even more serious if reports are accurate that Iranians have participated in this exercise".
He went on to insist that if North Korea reach the stage of miniaturising a nuclear device so it would fit on top of a missile "then the world is a much, much less safe place".
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