U.S. President Donald Trump and North Korean leader Kim Jong Un are set to hold their second summit on Wednesday and Thursday in Vietnam as they bid to break an impasse over Pyongyang's possession of nuclear weapons and ballistic missiles.

After reaching a vague denuclearization agreement in the first-ever U.S.-North Korea summit in June last year in Singapore, Trump and Kim are expected to broach the possible dismantlement of North Korea's main nuclear complex in Yongbyon in exchange for a declaration of a formal end to the 1950-1953 Korean War or partial sanctions relief, according to analysts.

Meeting in the Vietnamese capital Hanoi, the two leaders are unlikely to agree to sweeping denuclearization steps such as hammering out a road map for constraining -- and eventually eliminating -- nuclear weapons and ballistic missiles in North Korea based on a full account of its weapons programs.

(Journalists gather outside a Vietnamese government facility in Hanoi where North Korean officials plan to stay ahead of the summit)

Pyongyang has rejected a declaration of an inventory of its weapons arsenal -- a bedrock of effective, verifiable denuclearization -- claiming it would amount to giving the United States a list of targets.

Instead, Trump and Kim are expected to aim for incremental, action-for-action progress, as sought by Pyongyang, toward what the Trump administration says is the final, fully verified denuclearization of North Korea.

Such a piecemeal deal, analysts say, would involve the scrapping of Yongbyon, and perhaps other weapons sites in North Korea, in exchange for what Pyongyang says are "corresponding measures" from Washington.

Kim has suggested he could talk about dismantling the complex, capping the amount of fissile material it produces, or possibly granting access to international inspectors.

Closing Yongbyon would not lead to a reduction of what experts estimate is North Korea's stockpile of 30 to 60 nuclear warheads. But a complete and verifiable dismantlement of the complex, which houses facilities to produce plutonium and highly enriched uranium, would significantly curb production of new nuclear weapons, experts say.

Some, meanwhile, argue that Yongbyon is so old that closing it would be of little value.

Trump said he is in "no rush" to denuclearize North Korea, as long as the country continues to suspend nuclear and missile tests. In what may be an attempt to lower expectations for the Hanoi summit, Trump has hinted at the possibility of holding a third meeting with Kim.

"His goal is not denuclearization, but rather the cessation of their nuclear and missile testing," said Evans Revere, a nonresident senior fellow at the Brookings Institution, a Washington think tank.

After Kim pledged in the Singapore summit to work toward "complete" denuclearization of the Korean Peninsula, Trump proclaimed, "There is no longer a nuclear threat from North Korea."

[Getty/Kyodo]

"Whatever North Korea and the U.S. ultimately agree to in Hanoi, what is certain is that President Trump is going to walk away from Hanoi claiming victory, even though North Korea is unlikely to deliver a timetable for disarmament or declaration for all of its existing stockpiles," said Sue Mi Terry, senior fellow and Korea chair at the Center for Strategic and International Studies in Washington.

Given the broadly shared view that North Korea's likely goal is to win international recognition as a nuclear state, Revere said, "For Kim, the goal is to create the illusion of denuclearization."

"At a second Trump-Kim summit, expect Kim to offer concessions that support that illusion, but that do nothing to actually end his nuclear weapons program," he said.

Aside from Yongbyon, North Korea is likely to offer to extend its nuclear and missile testing hiatus, to promise to limit its existing arsenal, as well as to allow the United States and other parties to verify the shuttering of Pyongyang's main missile engine test site and the closure of the only known nuclear test site, analysts said.

Corresponding measures from the United States could include continued suspension of joint military exercises with South Korea, allowing South Korea to seek to exempt inter-Korean economic cooperation projects from U.N. sanctions on North Korea, as well as opening a liaison office in Pyongyang, they said.

But Terry noted that if Trump offers an end-of-war declaration, which Pyongyang has sought as a first step toward guaranteeing its security, it would undermine the rationale for the continued stationing of U.S. troops on the Korean Peninsula.

The Korean War ended in an armistice, not a peace treaty, meaning U.S.-led U.N. forces, including South Korea, are technically still at war with North Korea.

"If the Korean War is formerly over and there's a peace declaration and South and North Korea are in a state of peace, what is the rationale for keeping U.S. troops in South Korea?" Terry asked.

Senior U.S. officials denied Washington and Pyongyang were discussing a possible withdrawal of about 28,500 American troops from South Korea, a development that, if realized, would alter power balance of Northeast Asia, including Japan.

But Trump has referred to such a withdrawal, citing the "very expensive" costs involved in stationing armed forces in South Korea. "Maybe someday -- I mean, who knows?" he said earlier this month when speaking about a possible drawdown.