A flurry of diplomacy at this year's U.N. General Assembly session has put stalled denuclearization talks between the United States and North Korea back on track, with President Donald Trump announcing he will hold a second summit with its leader Kim Jong Un "in the not too distant future."

U.N. member states have supported Washington's engagement with Pyongyang. But experts are concerned the two leaders holding a meeting without any prospect of achieving substantial progress on denuclearization would amount to a de facto U.S. recognition of North Korea as a nuclear state.

In New York on Wednesday, U.S. Secretary of State Mike Pompeo met North Korean Foreign Minister Ri Yong Ho and agreed to visit Pyongyang in October to prepare for a second summit, an event South Korean President Moon Jae In said could occur by the end of the year.

(Getty/Kyodo)

Pompeo cancelled a planned trip to the North Korean capital in late August due to a lack of credible action by Pyongyang, despite Kim pledging to work toward "complete" denuclearization of the Korean Peninsula in the first-ever U.S.-North Korea summit in June in Singapore.

The renewed momentum came after Kim promised in a Sept. 18-19 meeting with Moon in Pyongyang to dismantle North Korea's key missile test site under the watch of international experts.

Kim also voiced willingness to decommission the country's main nuclear complex if the United States takes "corresponding measures," which would likely include a declaration of a formal end to the Korean War and the easing of sanctions.

Speaking in an interview on Tuesday with Fox News in New York, Moon said he, Kim and Trump have shared the broad understanding that they should make an end-of-war declaration at an early date, raising speculation that they may do so by the year-end as sought by the two divided Koreas.

The 1950-1953 conflict ended in an armistice, not a peace treaty, meaning U.S.-led United Nations forces, including South Korea, are technically still at war with North Korea.

North Korea wants an end-of-war declaration as a first step toward guaranteeing its security. But experts say Washington has compromised enough with Pyongyang when Trump suspended joint military exercises with South Korea after the Singapore summit.

"Before we go down the path of the second summit, we need to have some clarity," said Evans Revere, a nonresident senior fellow at the Brookings Institution, a Washington think tank. "Are the North Koreans going to commit themselves to the denuclearization of the North? If they are, what is the timeframe for that? What are the specifics?"

Besides, Kim's offer to dismantle the missile engine test site and launch pad in Tongchang-ri and the nuclear complex in Yongbyon was short of steps that U.S. policymakers have been pushing for, such as providing a full account of its nuclear weapons, related facilities and fissile materials, subject to verification by organizations such as the International Atomic Energy Agency.

"While North Korea has stopped testing missiles and nuclear devices, they have NOT moved toward denuclearization," Sen. Lindsey Graham, a Republican member of the Armed Services Committee, tweeted. "South Korea should not be played by Kim Jong Un."

Although Trump showed confidence to "make a deal" with Kim, analysts say the president should not rush to set up a second summit with the North Korean leader and make an end-of-war declaration without Pyongyang taking complete, verifiable and irreversible steps toward denuclearization.

To the North Koreans, according to Revere, the "denuclearization of the Korean Peninsula" means the end of the U.S.-South Korea alliance, the withdrawal of American troops from the peninsula and the removal of U.S. strategic assets that could be deployed in the event of a conflict.

"Is the DPRK prepared to issue a declaration of the number of weapons it has, the amount of plutonium and enriched uranium?" Revere said, referring to North Korea by the acronym for its formal name, the Democratic People's Republic of Korea.

"There are many things that we should be asking for in advance of (a Trump-Kim summit)," such as where its nuclear facilities are and how quickly they are prepared to allow the IAEA, other international organizations, the United States and others to come to North Korea to begin the process of dismantling them.

Dismissing Pyongyang's demand for an end-of-war declaration without abandoning nuclear weapons and ballistic missiles, Revere said, "Declaring an end to the Korean War in part undermines the rationale for the continued stationing of U.S. troops on the Korean Peninsula."

"That's something that North Korea wants, but it's not something that we should give them," he said.

Given North Korea's track record of using denuclearization talks to extract aid and other concessions while covertly continuing development of nuclear weapons and ballistic missiles, Bruce Klingner, the senior research fellow for Northeast Asia at the Heritage Foundation, a Washington think tank, said, "Don't lower your guard prematurely."

"And that's a peace declaration or a peace treaty until we deal with the North Korean threat -- not only the nuclear but also the missile and the conventional force threat," Klingner said. "Prior to that, it would be premature to sign a peace declaration or a peace treaty."

In a U.N. Security Council meeting on North Korea's denuclearization on Thursday, Japanese Foreign Minister Taro Kono said that while Tokyo backs diplomatic initiatives by Washington and Seoul over Pyongyang, "We are acutely aware that the IAEA's most recent report expressed 'grave concern' that North Korea continues its nuclear program."