The world moved closer to tightening sanctions on North Korea for its latest nuclear test after the US and China reached agreement on a new draft resolution to punish the country.
In response, Pyongyang threatened to cancel the 1953 ceasefire that ended the Korean War.
The UN Security Council was set to hold closed consultations on North Korea and non-proliferation as tensions on the Korean Peninsula soared again over the February test. UN diplomatic sources said the US was expected to circulate the draft resolution on sanctions to the full council Members were then expected to send the draft to their capitals for review.
Any fresh international sanctions are certain to infuriate North Korea, which has claimed the right to build nuclear weapons to deter alleged US aggression. Citing the US-led push for sanctions, the Korean People's Army Supreme Command warned of "surgical strikes" meant to unify the divided Korean Peninsula and of an indigenous, "precision nuclear striking tool". China is North Korea's closest ally, but it has indicated it is concerned about Pyongyang's behaviour.
Hours after North Korea carried out its third atomic blast on February 12, all 15 council members condemned the test and pledged further action. The swift, unanimous response from the UN's most powerful body set the stage for a fourth round of sanctions.
For the last three weeks the United States, a close ally of South Korea and Japan, has been negotiating the text of a new resolution with China. Politicians in Washington this week are also pushing for tougher US financial restrictions on North Korea, which have been tried before with significant impact but have upset China.
North Korea's neighbours and the West condemn the North's efforts to develop nuclear missiles capable of hitting the United States as a serious threat to north-east Asia's delicate security and a drain on resources that could go to North Korea's largely destitute people.
North Korea says its nuclear programme is a response to US hostility that dates back to the 1950-53 Korean War, which ended with an armistice, not a peace treaty, leaving the Korean Peninsula still technically in a state of war. The United States removed its atomic bombs from South Korea in 1991 and has repeatedly rejected North Korea's claims of US invasion plans. North Korea's three nuclear tests - in 2006, 2009 and 2013 - occurred after Pyongyang was condemned by the United Nations for rocket launches.
The Security Council imposed sanctions after the first two nuclear tests and after the North's rocket launch in December, which was viewed as part of the country's covert programme to develop ballistic missiles that can carry nuclear warheads.
The North's latest nuclear test was seen as a crucial step toward its goal of building a bomb small enough to be fitted on a missile capable of striking the United States. Many outside analysts still believe the North hasn't achieved such a miniaturisation technology.