TOKYO ­— North Korean leader Kim Jong Un has vowed to implement "new policies" to boost the country's nuclear deterrent, state media reported Sunday, underlining his decision to turn his back on denuclearization talks with the United States.

Kim made the call at a meeting of the ruling Workers’ Party’s Central Military Commission, nearly two years after he met President Trump at a historic summit in Singapore that seemed to offer hope of progress between the two nations.

Subsequent talks made little progress before dissolving in acrimony last year, and North Korea has since returned to a harder line in its public posturing.

Kim’s attendance at the meeting was his first public appearance in three weeks, with the country still on high alert over coronavirus. A three-week period out of the public eye last month provoked intense speculation about Kim’s health before he reappeared to open a fertilizer factory.

Central Military Commission members discussed measures to bolster the armed forces and “reliably contain the persistent big or small military threats from the hostile forces,” the state Korea Central News Agency reported.

“Set forth at the meeting were new policies for further increasing the nuclear war deterrence of the country and putting the strategic armed forces on a high alert operation,” the agency reported.

MIT professor Vipin Narang called the statement “alarming.”

“I have no idea what this means but I am sure we won’t like it,” he tweeted.

Leif-Eric Easley, a professor at Ewha University in Seoul, said it was probably a coincidence that the announcement was made just after it emerged that the Trump administration had discussed whether to conduct the country’s first nuclear test since 1992.

“The intention in Washington for pondering such a move may be to pressure Russia and China to improve arms control commitments and enforcement,” he wrote in an email. “But not only might this tack encourage more nuclear risk-taking by those countries, it could provide Pyongyang an excuse for its next provocation.”

The Korea Central News Agency said the military commission also decided to implement “crucial measures for considerably increasing the firepower strike ability of the artillery pieces of the Korean People’s Army.”