Subsequent to the tension with South Korea in last month, North Korea made a threatening statement again.
Pyongyang declared being ready to use nuclear weapons. It would be willing to revenge the US against its "anachronistic hostile policy."
International Business Times: North Korea threatens US with nuclear weapon attack after uranium enrichment plant restart
Nuclear production at Yongbyon had been shut down since 2007. However, Kim Jong-un implied the restart of its operation in 2013. It is not surprising that nuclear armament is ongoing in North Korea.
It is not sure how much the plan of North Korea is proceeding and whether the nuclear attack is technically feasible. Besides the concentration of radioactive substance, the development of intercontinental flying missiles is also challenging. North Korea has failed to launching satellites several times. In addition, the financial situation in North Korea is very poor. Expanding the budget for military seems wasting of money so that it is no more able to continue the research of weapons.
Even if North Korea has already developed the technique to attack Washington or New York completely, stabbing the US is not a wise idea at all. The US would revenge it immediately, leading the elimination of North Korean government.
Obviously, Kim can predict the result. Therefore, I do not think the threatening of North Korea is a real risk of war. The most worrying matter is the possibility for Kim to underestimate the response of the US. In the Gulf War, Saddam Hussein prospected that the US would not intervene the invasion of Iraq into Kuwait. It was a wrong estimation, and Iraq army was defeated by the multi-nation alliance led by the US very soon.
The US and other Western countries including Japan should continue to send the message to North Korea that, the use nuclear weapons is never permitted, otherwise it will be countered by the entire revenge. North Korea is likely to offer a barter between the abandonment of nuclear weapons and financial aids from Western countries. It will rather affordable, because continuous communication, even if it is filled with tension and disguise, is effective to construct mutual relationship, leading the lesser risk of war.