(CNN) A UN official who just returned from Pyongyang, where he spent several days speaking with North Korean officials, has said he is "really worried about an accidental move toward conflict."

Jeffrey Feltman, an American who is the United Nations undersecretary-general for political affairs, told CNN's Christiane Amanpour on Thursday that he is concerned about a "lack of communication" and the "high risk of some kind of miscalculation."

Tensions between North Korea and the United States have risen markedly in the past year. Pyongyang's weapons programs have passed critical thresholds this year, to the point where many in Washington consider North Korea's nuclear capability an imminent threat.

Feltman is the highest-level UN official to visit Pyongyang since 2011. He spent more than 15 hours speaking with North Korean officials, he said, including the foreign minister. Feltman has previously served as an American assistant secretary of state.

"The lack of trust in their mind meant that they had to rely on deterrence -- meaning military deterrence -- rather than on diplomatic dialogue in the short term."

In the long-term, he said they understood the need for diplomacy.

"I think that at least in terms of long-term aspirations, they understand that there has to be peaceful denuclearization of the Korean Peninsula, that there has to be some kind of arrangement that's based on a diplomatic solution."

During the presidential campaign, Donald Trump said he was open to sitting down with North Korean leader Kim Jong Un, but since his election his tone has been more confrontational.

Previous attempts to find a diplomatic solution to stymie North Korea's nuclear aspirations have failed. Policy makers in Washington have appeared reticent to start a new round of negotiations until Kim's regime makes some sort of effort to show it will negotiate in good faith, and not cheat on its agreements. What that signal is, and whether there are any preconditions that must be met before talks begin, has been the subject of open debate. The White House and the State Department appear to be at odds over the issue.

A North Korean official, however, told CNN in October that "before we can engage in diplomacy with the Trump administration, we want to send a clear message that the DPRK has a reliable defensive and offensive capability to counter any aggression from the United States."

'Sleepwalking into war'

Feltman's boss, UN Secretary-General Antonio Guterres, said in Tokyo Thursday that it is urgent for all sides to find a solution to the crisis. Some observers worry Trump's unorthodox style and heated. rhetoric could help fuel miscalculations that lead to conflict.

"We all want to avoid that things get out of control and that misperceptions and mishandling of situations make us sleepwalk into a war that will have devastating consequences," Guterres said at a news conference.

US Sen. Lindsey Graham, a Republican foreign policy hawk who serves on the Senate Armed Services Committee, said Wednesday he has a gut feeling there is a 30% chance U Trump orders a first strike on North Korea while also noting the extreme cost of a potential conflict on the Korean Peninsula

"War with North Korea is an all-out war against the regime," he said. "There is no surgical strike option. So if you ever use the military option, it's not to just neutralize their nuclear facilities — you gotta be willing to take the regime completely down."

North Korean officials are quite focused on those types of statements coming from Washington, Feltman said.

Feltman said he reminded North Korean officials that their nuclear and missile programs are a concern not just for the United States, but for the whole global community, as reflected through UN Security Council resolutions.

He did tell Amanpour, however, that North Korean officials were fully engaged in his talks.

"I have been in many diplomatic meetings where one side of the table or maybe both sides of the table simply read talking points and give long monologues to each other that repeat well-known positions or polemics and vitriol. That's not what happened. They listened extremely carefully to the points that we were making over the 4½ days that we were in Pyongyang."

"I don't know if they'll accept anything that we said. But they gave us a fair hearing about why the international community was so alarmed."