North Korean leader Kim Jong-un has visited the test site of a new tactical weapon in his first such public inspection since last year, hailing it as a "display of our rapidly-growing defence capabilities," state media said.
The North's first mention of a new weapons development in months threatens to sour the political atmosphere as negotiations between Pyongyang and the United States appear to have stalled.
"This result today is a justification of the party's policy focused on defense science and technology, another display of our rapidly-growing defense capabilities to the whole region, and a groundbreaking change in strengthening our military's combat capabilities," Mr Kim said.
The test was successful and the weapon could protect North Korea like a "steel wall," its KCNA news agency said, adding that Mr Kim had observed "the power of the tactical weapon".
The only picture released by state media showed Mr Kim standing on a beach surrounded by officials in military uniforms, but no weapons were visible.
International weapons experts said the officials around Mr Kim included a leader of the artillery corps of the Korean People's Army.
In Washington, in response to the North Korean announcement, a US State Department spokesman said: "We remain confident that the promises made by President Trump and Chairman Kim will be fulfilled."
The official was referring to an unprecedented summit of US President Donald Trump and Mr Kim in Singapore in June, where they agreed to work toward denuclearisation and peace on the Korean peninsula, and establish new relations with each other.
But the agreement was short on specifics, and negotiations have made little headway since.
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South Korea's defence ministry said it did not have an immediate comment but was preparing a statement on the North Korean test.
Mr Kim said the weapons system tested was one in which his father, Kim Jong-Il, had taken a special interest during his lifetime, personally leading its development.
Mr Kim's last publicised military inspection was the launch of the Hwasong-15 intercontinental ballistic missile (ICBM) on 29 November last year, though he engaged in at least eight other military related activities this year, the South's Unification Ministry said.
Mr Kim this year declared his nuclear force "complete" and said he would focus on economic development.
North Korea has continued to showcase its conventional military capabilities, including at a large military parade in Pyongyang, its capital, on 9 September.
But any testing of new weapons threatens to raise tension with Washington, which has said there will be no easing in international sanctions until North Korea takes more concrete steps to abandon its nuclear weapons or long-range missiles.
Pyongyang has increasingly expressed frustrations at Washington's refusal to ease sanctions, and recently threatened to restart development of its nuclear weapons if more concessions were not made.
A meeting in New York planned this month between US Secretary of State Mike Pompeo and North Korea's Kim Yong Chol, a senior aide to Mr Kim, was postponed.
Yesterday, US Vice President Mike Pence said Mr Trump planned to meet Mr Kim again in 2019 and will push for a concrete plan outlining Pyongyang's moves to end its arms programmes.
Meanwhile, Mr Pompeo has thanked North Korea and Sweden for cooperating to secure the release of a US citizen, Bruce Byron Lowrance, who had been detained by North Korea since entering the country illegally from China last month.
"The United States appreciates the cooperation of the Democratic People's Republic of Korea and the embassy of Sweden in facilitating the release of an American citizen," Mr Pompeo said in a statement, which did not identify the American.
