US stresses security commitment to South Korea after alleged North Korean underwater nuclear test

The United States on January 19 reiterated its security commitment to South Korea and Japan after North Korea claimed to have tested an underwater nuclear weapons system under development in waters off its east coast.

The North's defence ministry said the country conducted an "important" test of the Haeil-5-23 system, denouncing this week's naval drills between South Korea, the US and Japan as "reckless confrontation hysteria", according to Korean Central News Agency (KCNA).

"We have been very clear on the threat posed by the Democratic People's Republic of Korea (DPRK) military programs, and our commitment to the defence of the ROK, Japan, and our commitment to upholding regional peace and stability," a Pentagon spokesperson said in response to a question from Yonhap News Agency.

"We will continue to work with both the ROK and Japanese governments to address the threats posed by the DPRK," the official added.

ROK stands for South Korea's official name, the Republic of Korea, while DPRK is the acronym for the North's official name.

The spokesperson declined to elaborate on the weapons test, saying the Defense Department does not comment on intelligence matters.

South Korea, the US and Japan jointly conducted naval drills that involved USS Carl Vinson (CVN 70), a Nimitz-class aircraft carrier, from Monday to Wednesday, following Pyongyang's latest launch of a hypersonic missile.