Two North Koreans, including a military officer, defected to the South early on Saturday morning in the latest upset for Pyongyang after a fractious week in which Kim Jong-un threatened to pull out of June talks with Donald Trump, the US president.

The officer and a civilian defected by boat and were picked up by the South Korean military in the Yellow Sea, near the inter-Korean sea border, after expressing willingness to defect, reported the South’s newswire, Yonhap.

The defection, the first of a North Korean military officer since 2008, is awkward timing for Seoul, which has a longstanding policy of accepting any North Korean defectors who want to live in the South.

Moon Jae-in, South Korea’s president, has been at pains to keep this year’s diplomatic détente between North and South on track, particularly in the run up to June 12 summit in Singapore between Kim and President Trump, which aims to make progress on denuclearisation and peace on the peninsula.

But despite a friendly first meeting between Kim and Mr Moon at the end of April, during which they held hands as they crossed their shared border, the diplomatic thaw that began in January showed the first signs of a breakdown last week, and the latest defection could raise tensions further.