North Korean leader Kim Jong Un inspected the testing of a newly developed tactical weapon, calling it "another display of our rapidly-growing defense capabilities to the whole region," North Korean state media said on Friday.

It was the first mention by state media of a new development in North Korea's weapons program in months.

"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," Kim said.

KCNA said the test was successful.

In response, the United States said it remains confident that promises made by President Donald Trump and Kim at their Singapore summit will be fulfilled, according to a U.S. State Department spokesman on Thursday.

"We remain confident that the promises made by President Trump and Chairman Kim will be fulfilled," the spokesman said in a statement.

Kim said that the weapons system tested was one that his father, Kim Jong Il, was especially interested during his lifetime and led the development of personally.

This is Kim's first field visit to a testing site since his unprecedented summit with Trump in June, when the two leaders agreed to work toward denuclearization and peace on the Korean peninsula, and to establish new relations between the United States and North Korea.

The agreement was short on specifics, and negotiations have made little headway since, however.

A North Korean delegation is currently in South Korea visiting economic-related sites as part of inter-Korean reconciliation efforts.

Any testing of new weapons is likely to raise tensions 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.

The White House referred questions about the latest development to the State Department, which did not immediately respond to a request for comment.

Trump on Tuesday criticized what he called "inaccurate" media reports that North Korea had not declared an estimated 20 missile bases and added in a tweet: "I will be the first to let you know if things go bad!"

U.S. Secretary of State Mike Pompeo had been due to meet North Korea's Kim Yong Chol, a senior aide to Kim Jong Un, in New York earlier this month, but it was postponed to a later date.

U.S. Vice President Mike Pence said on Thursday Trump plans to meet Kim Jong Un again in 2019 and will push for a concrete plan outlining Pyongyang's moves to end its arms programs.