A guard post is seen near the demilitarized zone separating the two Koreas, in Paju, South Korea, May 16, 2018. Photo: Reuters / Kim Hong-Ji.

South Korea said on Thursday it intends to play the role of mediator after North Korea threatened to pull out of a summit with the United States aimed at the denuclearisation of the Korean peninsula.

North Korea on Wednesday said it might not attend the June 12 summit in Singapore if the United States continued to demand it unilaterally abandon its nuclear arsenal, which it has developed in defiance of UN Security Council resolutions to counter perceived US hostility.

Doubts over the summit between North Korean leader Kim Jong-un and US President Donald Trump arose on Wednesday when Pyongyang denounced US-South Korean military exercises as a provocation and called off high-level talks with Seoul.

South Korean Foreign Minister Kang Kyung-wha told parliament that North Korea and the United States had differences of views over how to achieve denuclearisation. Trump acknowledged on Wednesday it was unclear if the summit would go ahead.

“It is true that there are differences of opinion between the North and the United States on methods to accomplish denuclearization,” Kang told lawmakers, according to Yonhap News Agency.

A South Korean presidential Blue House official said the South intends to more actively perform “the role of a mediator” between the United States and North Korea.

Trump will host South Korean President Moon Jae-in at the White House on May 22.

The Blue House intends to “sufficiently convey (to the United States) what we’ve discerned about North Korea’s position and attitude… and sufficiently convey the United States’ position to North Korea,” thereby helping to bridge the gap, the official said.

Asked if she trusted Kim Jong-un, South Korean Foreign Minister Kang said: “Yes.”

Japan’s Asahi newspaper reported that the United States had demanded North Korea ship some nuclear warheads, an intercontinental ballistic missile and other nuclear material overseas within six months.

The newspaper, citing several sources familiar with North Korea, said US Secretary of State Mike Pompeo appeared to have told the North Korean leader when they met this month that Pyongyang might be removed from a list of state sponsors of terrorism if it complied.

The Asahi also reported that if North Korea agreed to complete, verifiable and irreversible denuclearization at the Singapore summit, Washington was considering giving guarantees for Kim’s regime.

China’s top diplomat, Wang Yi, said the measures North Korea has taken to ease tension should be acknowledged, and all other parties, especially the United States, should cherish the opportunity for peace.

Cancellation of the summit, the first between US and North Korean leaders, would deal a major blow to what could be the biggest diplomatic achievement of Trump’s presidency.

North Korea defends its nuclear and missile programs as a deterrent against perceived aggression by the United States, which keeps 28,500 troops in South Korea, a legacy of the 1950-53 Korean War, which ended in a truce, not a peace treaty.

The North has long said it is open to eventually giving up its nuclear arsenal if the United States withdraws its troops from South Korea and ends its “nuclear umbrella” alliance with Seoul.

North Korea said it was pulling out of the talks with South Korea after denouncing US-South Korean “Max Thunder” air combat drills, which it said involved US stealth fighters, B-52 bombers and “nuclear assets.”

Speaking to reporters in Brussels on Wednesday, UN Secretary-General Antonio Guterres said: “I hope that in the end common sense will prevail, and the summit will take place and it will be successful.”