Yellen will meet with senior South Korean officials as part of a trip to Asia to attend a meeting of finance officials from the Group of 20 major economies, the sources said.

A Treasury spokesperson declined to comment.

Details are not yet finalised but Yellen could have talks with South Korean foreign minister Park Jin and finance minister Choo Kyung-ho to discuss North Korea as intelligence officials on both sides of the Pacific are concerned it is preparing to conduct its first nuclear test in five years.

North Korean leader Kim Jong Un ordered a strengthening of defence capabilities as he wrapped up a meeting with top military officials, state media said on Friday, leading to speculation in South Korea that Pyongyang could possibly be adding tactical nuclear weapons to its arsenal.

Last week, Park told a press conference after his meeting with US secretary of state Antony Blinken that the two allies “need to push for a new UN Security Council resolution to deal with North Korea’s provocation” and that Pyongyang “will be met with a united and firm response from the alliance and the international community” should they go ahead with the test.

North Korea’s isolation from the global financial system has also made it more resilient to sanctions imposed by the US and other countries.

Discussions on economic conditions are also set to be on the agenda for Yellen’s trip as both Washington and Seoul struggle to tamp down inflation rates that have angered consumers.