In a statement, a spokesperson for North Korea's defense ministry accused the United States of increasing nuclear threats, citing joint military drills with South Korea and sending a strategic nuclear submarine, the state-run KCNA report said.
The North Korean military will counter the US military strategy with the "most overwhelming and sustained response strategy," the spokesperson said, citing an addition to the country's constitution, Reuters reported.
North Korea last week adopted a constitutional amendment to enshrine its policy on nuclear force, as leader Kim Jong Un pledged to accelerate production of nuclear weapons to deter US provocations, according to state media.
South Korea's defense ministry criticized the move in a statement on Wednesday, saying Pyongyang will be "further isolated" internationally, which would "worsen" the suffering of North Koreans.
Any use of nuclear weapons by Pyongyang will bring the Pyongyang government to an end, the ministry added, echoing President Yoon Suk Yeol's remark last month.
The spokesperson for North Korea's defense ministry also criticized the US military's Sept. 28 strategy statement for its descriptions of China as the "pacing challenge" and Russia as an "acute threat", calling it a "political provocation" against independent sovereign states.
Unification minister Kim Yung-ho told reporters in Germany on Tuesday that the situation for inter-Korean exchange was "being monitored," according to news agency Yonhap.