U.S. Secretary of State Mike Pompeo arrives at Haneda Airport, in Tokyo, Japan, Saturday, July 7, 2018. Andrew Harnik/Pool via REUTERS

SEOUL (Reuters) - North Korea said on Saturday its “firm, steadfast” resolve to give up its nuclear programs may falter after the United States demanded unilateral denuclearisation during two days of talks in Pyongyang, state media said.

The North’s official KCNA news agency said the result of talks with the delegation headed by U.S. Secretary of State Mike Pompeo was “extremely troubling,” accusing it of insisting on complete, verifiable and irreversible denuclearisation.

The “fastest way” to achieve a nuclear-free Korean peninsula was through a phased approach under which both sides took steps at the same time, KCNA said in a statement citing an unnamed foreign ministry spokesperson.