North Korea claims it has succeeded in miniaturising its nuclear weapons, a development which could allow them to be delivered by missile.
"It has been a long time since we began miniaturising and diversifying our means of nuclear strike," the powerful National Defence Commission (NDC) said in a statement carried by the official Korean Central News Agency.
"We have also reached the stage where the highest accuracy rate is guaranteed not only for short- and medium-range missiles but long-range missiles as well. We don't hide this fact."
The NDC, the country's highest military body chaired by leader Kim Jong-un, berated the United States and its allies for condemning what the North described as a submarine-launched ballistic missile test on May 8.
Washington and its allies said the test was a breach of a United Nations ban on the North's use of ballistic missile technology.
A top US military official claimed on Tuesday, however, that purported photos of the North's missile launch had manipulated by state propagandists, and the isolated country may still be years away from developing the technology.
"They have not gotten as far as their clever video editors and spinmeisters would have us believe," said Admiral James Winnefeld, vice chair of the joint chiefs of staff.
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Meanwhile, UN Secretary-General Ban Ki-moon said that an invitation for him to visit the North's Kaesong Industrial Complex had been reversed.
"No explanation was given for this last-minute change," Ban said at a digital forum in Seoul.
"This decision by Pyongyang is deeply regrettable. However, I as the Secretary-General of the United Nations, will not spare any efforts to encourage the DPRK to work with the international community for peace and stability on the Korean peninsula and beyond."
Source: Al Jazeera and agencies