Alwaght-North Korea say the US has declared war on the country by its act of imposing sanctions on its leader Kim Jong Un.
The move by the US was described as “the worst hostile act” against the country in a statement issued by Pyongyang's foreign ministry carried by the official Korean Central News Agency.
The US Treasury Department imposed the sanctions on the North Korean leader and 10 other senior officials on Wednesday for alleged human rights violations. They are set to affect property and other assets within US jurisdiction.
In an initial response to the sanctions Pyongyang urged Washington to withdraw them immediately and threatened to instantly cut off all diplomatic channels if they failed to do so.
A statement said: "The United States has dared to challenge the highest authority of ours, committing the worst-ever hostile act that goes beyond confrontation over the so-called human rights issue. This constitutes an open declaration of a war.
"Now that the US has made a declaration of a war against us, all issues arising from relations with the US will forthwith be handled in accordance with DPRK's [the official acronym for North Korea] wartime laws."
Pyongyang will take "extremely strong countermeasures" in response, it added, without providing more details.
Last month North Korea tested its Musudan mid-range missile with a range of 3,500 kilometers saying it would allow strikes on US forces throughout the region.
Han Song Ryol, director-general of the department of US affairs at North Korea's Foreign Ministry, said that Washington can expect more nuclear tests and missile launches, like those earlier this week, if the US continues in its attempts to weaken the North Korean government through its policy of pressure and punishment.
“My country is a nuclear state. In the past, my country has been threatened by the United States with its nuclear weapons, but I can now say proudly that the United States is being threatened by my country's nuclear weapons,” Han said.
He said that there was a possibility of dialogue with the United States, but only on the condition that Washington agrees to “drop its hostile policies” and replace the armistice that ended the Korean War with a lasting peace treaty. He added that for a dialogue to take place, the US also has to withdraw its troops from South Korea.