SEOUL: South Korea said some North Korean officials returned to an inter-Korean liaison office on Monday, three days after the North abruptly withdrew its entire staff citing unspecified instructions from “higher-level authorities.” It wasn’t immediately clear why North Korea sent some workers back to the office or whether it would restore a full staff. The North’s decision to withdraw its staff on Friday came a week after its vice foreign minister threatened to pull out of nuclear negotiations with the United States following the collapse of a nuclear summit last month between leader Kim Jong Un and President Donald Trump. Seoul’s Unification Ministry, which deals with inter-Korean affairs, said in a statement that four to five North Korean officials showed up for work Monday at the liaison office in the North Korean border town of Kaesong and told South Korean officials they came to work their usual shifts. The ministry said the North continues to provide no clear explanation on why it withdrew staff from the office. The North reportedly sent about 10 workers each working day to the office since it opened last September as part of a slew of reconciliation steps between the rivals agreed to by Kim and South Korean President Moon Jae-in. The Koreas in past months have dismantled some of their front-line guard posts, halted military exercises across their border and vowed to resume inter-Korean economic projects when possible, voicing optimism that international sanctions could end and allow such projects. While Moon says inter-Korean reconciliation is crucial for achieving progress in nuclear negotiations, the breakdown of the Trump-Kim summit has created a difficult environment to push engagement with the North. Washington and Pyongyang have struggled with the sequencing of North Korea’s nuclear disarmament and the removal of US-led sanctions against the North, and blamed each other for the collapse of the summit. North Korean state media have recently demanded that South Korea distance itself from the US and resume joint economic projects that have been held back by sanctions.