The United States' special envoy for North Korea says it is "preparing for all contingencies", in close coordination with its South Korean and Japanese allies, as it monitors North Korean arrangements for a possible nuclear test explosion.
South Korean and US intelligence officials say they have detected North Korean efforts to prepare its north-eastern testing ground for another nuclear test.
The test would be North Korea's seventh since 2006 and the first since September 2017, when it claimed to have detonated a thermonuclear bomb to fit on its intercontinental ballistic missiles.
The US special representative for North Korea, Sung Kim, was in Seoul for a trilateral meeting with his South Korean and Japanese counterparts to discuss the growing threat posed by North Korea's nuclear weapons and missiles programs.
"This assessment is consistent with the DPRK's own recent public statements."
Aside from coordinating with Seoul and Tokyo over contingency planning, Washington is also prepared to make "both short- and longer-term adjustments to our military posture as appropriate and responding to any DPRK provocation and as necessary to strengthen both defence and deterrence to protect our allies in the region," Mr Kim said.
Funakoshi Takehiro, Japan's director-general for Asian and Oceanian Affairs, said the North's spate of ballistic tests this year and possible nuclear test preparations underscore the need for a more robust international response and lamented the UN Security Council's inaction over the North's recent tests.
Kim Gunn, South Korea's representative at the nuclear envoy, said North Korea's nuclear weapons and missile development would only strengthen the security cooperation between the US and its Asian allies and deepen the North's isolation and economic woes.
Nuclear negotiations between Washington and Pyongyang have stalled since 2019 over disagreements in exchanging the release of crippling US-led sanctions against North Korea and the North's disarmament steps.
North Korean leader Kim Jong Un has expanded his ballistic missile program amid the diplomatic pause and a nuclear test would escalate his brinkmanship aimed at cementing the North's status as a nuclear power and negotiating economic and security concessions from a position of strength.
North Korea has already conducted missile tests 17 different times in 2022, including its first ICBM demonstrations in nearly five years, exploiting a favourable environment to push forward weapons development as the UN Security Council remains divided over Russia's war on Ukraine.
Sung Kim said China and Russia were clearly not interested in working with the United States to manage North Korea's nuclear and missile arsenal, after Beijing and Moscow vetoed a US proposal for new sanctions.
Mr Kim said it was in the interest of China and Russia to cooperate with Washington, which is still seeking to engage with them to pressure Pyongyang.
Russia and China last week vetoed the US-sponsored resolution that would have imposed additional sanctions on North Korea over its latest ballistic tests on May 25, which South Korea's military said involved an ICBM flown on medium-range trajectory and two short-range weapons.
Those tests came as Mr Biden wrapped up his trip to South Korea and Japan, where he reaffirmed the US commitment to defend both allies in the face of the North's nuclear threat.
Linda Thomas-Greenfield, the US ambassador to the UN, said Washington will still push for additional sanctions if North Korea conducts a new nuclear test.
Kim Jong Un's pressure campaign is unlikely to be impeded by a deadly coronavirus outbreak in his largely unvaccinated autocracy.
ABC/wires
