A security adviser to South Korean President Moon Jae-in on Monday said Pyongyang is not willing to provide a list of its nuclear facilities and materials due to United States’ hostility toward it. 

Moon Chung-in, a special presidential adviser for unification, diplomacy and national security affairs, said he heard a top North Korea official saying that the country is reluctant to comply with the U.S. demands about submitting a nuclear list. The official also said the country is also not prepared to accept an international nuclear inspection before the official declaration to end the Korean War., he added.

Disclosing the remarks during a forum on Korean Peninsula peace in Seoul, the advisor, who had accompanied President Moon for his third summit with North Korean leader Kim Jong-un, called for a more flexible stance during negotiations with Pyongyang.

"On my recent trip to Pyongyang, I said to a high-ranking North Korean official that the North can build trust with the U.S. after providing its nuclear program list, accepting international nuclear inspection and signing an end-of-war declaration," the adviser said, Yonhap News Agency reported. "But the North's position was clear. The official told me his country cannot present a list of nuclear facilities and materials due to hostility from the U.S."

He said the U.S. approach to North Korea’s nuclear problem is considered inflexible and even idealistic.

 "I agree to complete, verifiable and irreversible denuclearization and that's certainly our goal. But if we adhere to this unpractical approach, the consequences are tragic and we should avoid such a situation from the beginning," he said.

He concluded by saying he agrees with Pyongyang’s stance that a non-aggression end-of-war declaration must be signed before the international inspection and before submitting the nuclear list. He also urged the U.S. to act flexibly with North Korea and not view Pyongyang as "wicked.”

Earlier this month, U.S. Secretary of State Mike Pompeo met North Korean leader Kim Jong Un during which the latter agreed to allow international inspectors to see the country’s Punggye-ri nuclear test site.

“There’s a lot of logistics that will be required to execute that, but when we get them, we’ll put them on the ground,” Pompeo said, adding that the “real progress” in the denuclearization talks would come at a second summit between Kim and President Donald Trump.

“Both the leaders believe there’s real progress that can be made, substantive progress that can be made at the next summit. And so we’re going to get (that meeting) at a time that works for each of the two leaders in a place that works for both of them. We’re not quite there yet, but we’ll get there,” Pompeo had said.