North Korea carries out biggest nuclear test
North Korea has carried out its third, most powerful nuclear test despite UN warnings, and said "even stronger" action might follow.
If, as North Korea reports, a smaller device was tested successfully, analysts say this could take Pyongyang closer to building a warhead small enough to arm a missile.
Punggye-ri nuclear test site. Site of Norths most recent test.
North Koreas nuclear test sites
Since Kim Jong-un succeeded his father, North Korea has continued to send out contradictory messages.
Mr Obama said the test was a "highly provocative act", and called for "swift" and "credible" international action in response.
China expressed "firm opposition" to its ally's test, urging the North to honour its commitment to denuclearisation and "not take any actions which might worsen the situation".
In other reaction:
- Russian Foreign Minister Sergei Lavrov said the North should "abandon its nuclear arms programme", and he called for the revival of talks on the issue
- South Korea's presidential national security adviser, Chun Young-woo, said the test was an "unacceptable threat to the security of the Korean peninsula and north-east Asia... and a challenge to the whole international community"
- Japanese Prime Minister Shinzo Abe said it was a "grave threat" to Japanese security and could "not be tolerated"
- Nato described the test as an "irresponsible act" and a "grave threat to international and regional peace, security and stability"
- Britain called for a "robust response" from the UN Security Council
- French President Francois Hollande condemned the test and said Paris would back firm action by the UN Security Council
The trouble, as ever, is what the international community can do in response without triggering an even bigger crisis - North Korea is already tied up in layers of sanctions which do not seem to have had any impact.
Some in Washington have talked of maybe targeting North Korean financial interests, but the only real pressure is seen to lie with China.
By defying the UN and launching its nuclear test now, Pyongyang is giving the new leadership in Beijing a very public test of its own.