By Josh Smith and Hyonhee Shin

SEOUL (Reuters) – Despite battling a wave of suspected COVID-19 infections, North Korea appears to be preparing to test an ICBM ahead of US President Joe Biden’s first trip to South Korea, South Korean and US officials said.

An ICBM test appeared imminent, Deputy National Security Advisor Kim Tae-hyo said at a briefing in Seoul.

“If there is a small or large North Korean provocation during the summit, we have prepared plan B,” he said.

This plan would secure the defensive posture and command and control systems of the combined US-South Korea armed forces, even if it required a change in the summit’s schedule, Kim said.

A US official said on condition of anonymity that the latest information showed North Korea could conduct an ICBM test as early as Thursday or Friday.

Biden is expected to arrive in South Korea on Friday and hold talks with his South Korean counterparts for several days before visiting Japan.

The White House said last week Biden was considering a trip to the demilitarized zone bordering North Korea, but Kim said that was unlikely.

A weapons test could overshadow Biden’s broader focus on China, trade and other regional issues, and underscore the lack of progress in denuclearization talks despite his administration’s promise to break the stalemate with practical approaches.

It could also complicate international efforts to offer aid to Pyongyang as it battles its first confirmed COVID outbreak.

The trip marks Biden’s first trip to the region as president and the first summit with South Korean President Yoon Suk-yeol, who took office on May 10.

Yoon has vowed to take a tougher line against North Korean “provocations” and is expected to seek greater assurances from Biden that the United States will step up its “enhanced deterrence” against the North.

The Yoon administration has urged the United States to deploy more nuclear-capable “strategic assets” such as long-range bombers, submarines and aircraft carriers in the region.

The chances of North Korea conducting a nuclear test this weekend appear slim, but if the North stages a major provocation, such means are ready to be mobilized, Kim said.

US officials had warned the North could test a nuclear weapon surrounding the visit, and the State Department said Tuesday there was no expectation that the COVID outbreak would change Pyongyang’s resolve to eventually resume nuclear testing, which had been suspended since 2017.

“Even as (North Korea) continues to refuse to donate … apparently much-needed COVID vaccines, they continue to invest untold sums in ballistic missile and nuclear weapons programs that do nothing to alleviate the humanitarian plight of the North Korean people.” ‘ State Department spokesman Ned Price said at a briefing.

According to a new report from the US-based Center for International and Strategic Studies (CSIS), commercial satellite imagery shows work continues at the nuclear site, whose underground test tunnels were closed in 2018 after leader Kim Jong Un imposed a moratorium on nuclear and ICBM tests had declared .

He has since stated that the country is no longer bound by that moratorium due to a lack of progress in talks with the United States. The North resumed testing ICBMs in March.

“The timing of this test is solely in the hands of Kim Jong Un,” the CSIS report on the nuclear site said.

North Korea has also restarted construction of a long-idle nuclear reactor that would increase its production of plutonium for nuclear weapons by a factor of 10, researchers at the US-based James Martin Center for Nonproliferation Studies (CNS) reported last week, citing satellite imagery.

Analysts say that even if North Korea tests a weapon, South Korea and the United States should offer unconditional COVID assistance.

North Korea sent planes to China to pick up medical supplies days after confirming its first COVID-19 outbreak, media reported Tuesday, but Pyongyang has yet to respond to offers of help from South Korea. Washington says it supports aid to North Korea but has no plans to provide vaccines at this time.

(Reporting by Idrees Ali in Washington and Josh Smith in Seoul; Additional reporting by Soo-hyang Choi. Editing by Gerry Doyle)