SEOUL (Reuters) - North Korea reversed a decision to pull out of an inter-Korean liaison office by sending some officials back to work on Monday, South Korea said, a turnaround that came after U.S. President Donald Trump opted not to impose extra sanctions on Pyongyang.

FILE PHOTO: The inter-Korean Kaesong Industrial Complex which is still shut down, is seen in this picture taken from the Dora observatory near the demilitarised zone separating the two Koreas, in Paju, South Korea, April 24, 2018. REUTERS/Kim Hong-Ji/File Photo

On Friday, North Korea had said it was quitting the office, just hours after Washington brought the first new sanctions on Pyongyang since a second U.S.-North Korea summit broke down last month.

The liaison office in Kaesong, North Korea, was opened in September, a key development in the past year of North-South detente. North Korea’s pullout was seen as a setback for South Korean President Moon Jae-in’s attempts to engage with Pyongyang.

On Friday, Trump said he decided against imposing new large-scale sanctions on North Korea over its nuclear weapons program, a move experts said could be an effort to defuse tensions.

South Korea’s Unification Ministry said some North Korean staff members were working at the liaison office on Monday and the two sides held a consultation. It quoted North Korean staff members as saying “we came to do our shift as usual.”

South Korea’s Yonhap news agency said four or five North Korean officials came to the office, about half the usual number, but none of the more senior officials showed up.

Analysts said the North Korean move probably reflected Pyongyang’s satisfaction with Trump’s decision to hold off on new sanctions. They said last week’s pullout appeared aimed at pressuring Seoul to persuade Washington to soft-pedal on sanctions.

The U.S. State Department declined to comment but confirmed a Japanese media report that the U.S. special representative for North Korea, Stephen Biegun, was currently visiting Beijing.

Japan’s Kyodo news agency quoted a diplomatic source as saying that Biegun’s visit may include talks with Chinese Vice Foreign Minister Kong Xuanyou.

The State Department declined to comment on Biegun’s schedule.

U.S. Secretary of State Mike Pompeo said on March 4 he was hopeful he could send a team to North Korea “in the next couple of weeks,” but there has been no sign of a North Korean willingness to extend such an invitation.

Separately, Russia’s RIA news agency quoted a Russian lawmaker as saying on Monday that North Korean leader Kim Jong Un will visit Russia for talks this spring or summer. The Kremlin confirmed a trip was being worked on but said that it was not able to provide further details.

Last month’s Trump-Kim summit collapsed over North Korean demands for sanctions relief and U.S. demands that North Korea give up its nuclear weapons. China said last year that Beijing, Moscow and Pyongyang believed it was necessary to consider adjusting U.N. sanctions at an appropriate time.