It came after the United Nations imposed tough new sanctions on North Korea over recent nuclear tests and a rocket launch.
The Pentagon said it is aware of the reports and closely monitoring the situation in coordination with regional allies.
Kim also warned that the situation on the divided Korean Peninsula had become so risky that the North needed to shift its military strategy to one of “pre-emptive attack”.
Kim has told military leaders to be prepared to launch pre-emptive strikes as he supervised training involving newly developed rocket launchers, the Korean Central News Agency reported.
Despite the North’s nuclear threats, the US raised doubts over North Korea’s ability to miniaturize a nuclear weapon and to load it on an intercontinental ballistic missile.
The news, released via North Korea’s state news agency KCNA, is a sign of increasing tension between the country and the rest of the world following newly tightened sanctions imposed by the UN.
Hours after the United Nations adopted the sanctions, North Korea fired six short-range projectiles into the sea in a new show of defiance.
Yang Moo-jin of the University of North Korean Studies said the firings were considered as a token response to the sanctions and North Korea is not expected to conduct a major launch until the Workers’ Party conventions scheduled in May.
This meeting took place on the basis of worldwide concern prompted by the threatening language of Kim Jong-Un.
“We urge the North to abandon its obsolete way of backbiting a state leader with vulgar language and act in a way that is helpful to the development of inter-Korean relations”, said the Unification Ministry.
Apart from its nuclear weapons, North Korea’s multiple-rocket launchers and artillery pieces are its most-feared weapons in the South. The North is estimated to have 13,000 of them clustered on the inter-Korean border, 28 miles north of Seoul.
The United States is building a network of ground-based missile interceptors created to counter a threat from countries such as North Korea.
On Friday, South Korea and the US began a working group to put together plans for the deployment of an advanced USA missile-defense shield in South Korea.
“Our government, as our president said, is trying our best to create an environment in which North Korea realizes that it can not survive with its nuclear program and that it will have to change itself”, Jeong said.
North Korea appears to be preparing to test a new rocket engine – satellite imagery has revealed.
China and Russian Federation oppose THAAD – which has powerful radar capable of penetrating deep into their countries.