North Korean leader Kim Jong Un is pictured during a test-fire of strategic submarine-launched ballistic missile in an image released by North Korea's Korean Central News Agency on Aug. 25. (Korean Central News Agency/Reuters)

U.S. experts and former officials secretly met several times with top North Korean officials this year, and some of them have emerged believing the regime of Kim Jong Un is ready to restart talks about its nuclear program.

There has been no official dialogue between the U.S. government and North Korea since Kim assumed power following his father’s death in 2011. But Pyongyang has quietly maintained contact with Washington through a series of “Track 2” dialogues. Pyongyang often sends senior diplomats to attend these sessions. The Americans who take part are former officials and top Korea and nuclear experts. The meetings have taken place in Berlin, Singapore and Beijing.

North Korea has drastically increased the pace of its nuclear and ballistic missile tests since the young Kim came to power, including with a successful submarine missile launch last week. Conventional wisdom in Washington is that there’s no chance for real dialogue with the regime. But that is a source of dispute among the Americans who are talking to North Korean officials.

A North Korean submarine-launched missile was fired toward Japan on Aug. 24, Seoul officials said, and flew about 300 miles in the longest missile flight the country has launched. (Video: Reuters / Photo: AP)

“The main thing they are interested in is replacing the current armistice with a peace treaty. In that context, they are willing to talk about denuclearization,” Joel Wit, a nuclear expert with the U.S.-Korea Institute, told me. “They made it fairly clear that they were willing to discuss their nuclear weapons program, that it would be on the table in the context of the peace treaty.”

Wit traveled to Berlin in February with other U.S. experts and met with Ri Yong Ho, who in May was promoted to North Korea’s foreign minister. He said the Pyongyang delegation sent signals that the door was open for resumed negotiations.

Robert Carlin, a former U.S. official and North Korea negotiator, was on the Berlin trip. In July, he wrote an article analyzing a new statement from North Korea in which Pyongyang also talked about denuclearization of the entire Korean Peninsula as part of a grand bargain with the United States.

Other Americans who have met recently with the North Koreans are skeptical that real signals are being sent or any real opening for negotiations has emerged. Victor Cha, the top Asia official at the National Security Council during the George W. Bush administration, was at the same meetings as Wit and Carlin but came away with the opposite conclusion.

“They don’t seem like they are speaking in a leaning-forward quasi-official capacity,” he said. “They seem to be just spouting talking points.”

Cha said the latest North Korean rhetoric is not substantively different from what the regime was saying before and that those who see signals of a new, more open stance from Pyongyang are engaged in wishful thinking. “In the past, you didn’t have to work as hard to find those signals,” he said.

The closest U.S. officials came to actually meeting directly with North Korean officials was in June, during a private conference in Beijing called the Northeast Asian Security Dialogue. Sung Kim, the State Department’s special representative for North Korea policy, was there, while Choe Son Hui, deputy director general of the North Korean foreign ministry’s U.S. affairs department, led Pyongyang’s delegation.

The State Department has said no formal meeting took place, but one participant told me Kim and Choe may have talked on the sidelines. During the conference, Choe laid out terms for a resumption of dialogue, according to that participant. Choe said Pyongyang will no longer discuss giving up existing nuclear assets but could strike a deal stopping a future buildup.

“To me, they were saying, ‘We’re here to send a message that the door is not closed to negotiations, we’re ready to talk, but don’t expect us to give up what we have,’” the participant said.

For many in Washington, including the White House, that position is a non-starter, because it means North Korea has no intention of living up to its previous commitments to denuclearize. This summer, the Obama administration has drastically increased sanctions on Pyongyang in response to Kim’s continued testing of nuclear bombs and ballistic missiles.

There’s probably no time for a new dialogue with Pyongyang to yield progress before the Obama administration departs. If Hillary Clinton is elected, her top aides have said they will also focus on increasing pressure on Kim through new sanctions before pursuing talks. That’s the playbook that was used with Iran.

But North Korea is not Iran. It already has enough material for perhaps a dozen bombs and could have enough for 79 weapons by the end of Clinton or Donald Trump’s first term, according to the Institute for Science and International Security. Multilateral sanctions with Pyongyang are less effective because the country only really depends on China, which is unlikely to economically strangle its problematic client state.

If the North Koreans are sending signals to Americans that they want to talk, the U.S. government has a responsibility to explore that possibility. But if North Korea is serious, it must send a clearer message and show greater willingness to end its belligerence.