North Korea's Parliament has adopted an amendment to the constitution to formulate the country's policy on nuclear force, state media KCNA reported.
The Supreme People's Assembly unanimously adopted "the crucial agenda item for formulating the DPRK's policy on the nuclear force as the basic law of the state," KCNA said on Thursday.
DPRK is the initials of the North's official name, the Democratic People's Republic of Korea.
Addressing the parliament, North Korean leader Kim Jong-un said it is "very important" to "accelerate the modernisation of nuclear weapons in order to hold the definite edge of strategic deterrence," KCNA said.
"This is a historic event that provided a powerful political lever for remarkably strengthening the national defence capabilities," Kim said, according to KCNA.
On Tuesday, the North Korean envoy told the UN that Pyongyang was on the brink of a nuclear war and had no choice but to accelerate its defences.
"The Korean peninsula is in a hair-trigger situation with imminent danger of nuclear war breakout," Ambassador Kim Song told the UN.
"Given the prevailing circumstances, the DPRK [North Korea] is urgently required to further accelerate the build-up of its self-defence capabilities to defend itself impregnably," he said.
Concerns over testings
North Korea has tested dozens of ballistic missiles in the past 18 months.
The United States has long warned that Pyongyang was ready to carry out a seventh nuclear test.
President Joe Biden's administration has repeatedly said that it is open to dialogue with North Korea without preconditions, but Pyongyang has shown no interest in working-level talks.
Biden's predecessor, Donald Trump, held three historic in-person meetings with Kim, succeeding in reducing tensions but not producing any lasting agreement.