North Korean leader Kim Jong Un shakes hands with Chinese President Xi Jinping in Beijing, as he paid an unofficial visit to China, in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang March 28, 2018. KCNA/via Reuters

TOKYO (Reuters) - North Korean leader Kim Jong Un told Chinese President Xi Jinping during talks in Beijing last week that he agreed to return to six-party talks on his nation’s nuclear program and missile tests, the Nikkei newspaper said on Thursday.

Months of chill between Beijing and Pyongyang appeared to suddenly vanish during Kim’s secretive visit, with China saying that Kim had pledged his commitment to denuclearization.

Quoting multiple sources connected to China and North Korea, the Nikkei said that, according to documents issued after Kim and Xi met, Kim told Xi that he agreed to resuming the six-party talks, which were last held in 2009.

North Korea declared the on-again, off-again talks dead at the time, blaming U.S. aggression. The talks grouped the two Koreas, the United States, Russia, Japan and host China.

The sources said it was also possible that Kim could convey his willingness to resume the talks to U.S. President Donald Trump at a summit set to take place in May, but that it was far from clear if that meant the talks would actually resume.

Chinese officials were not immediately able to comment.

China has traditionally been secretive North Korea’s closest ally, though ties have been frayed by Kim’s pursuit of nuclear weapons and missiles and Beijing’s backing of tough U.N. sanctions in response.

North Korea has said in previous talks that it could consider giving up its nuclear arsenal if the United States removed its troops from South Korea and withdrew its so-called nuclear umbrella of deterrence from South Korea and Japan.

Some analysts have said Trump’s willingness to meet Kim handed North Korea a diplomatic win, as the United States had insisted for years that any such summit be preceded by North Korean steps to denuclearize.