WASHINGTON - President Donald Trump met with a senior North Korean official at the White House on Friday amid speculation that the two sides could soon announce a second summit between him and Kim Jong Un.

Trump welcomed Kim Yong Chol, a former spy chief, who was reported to be delivering a personal letter from North Korea's authoritarian leader. Chol, who has served as Pyongyang's lead negotiator on nuclear talks, also visited Trump in the Oval Office in June to seal plans for the first summit later that month in Singapore.

"They will discuss relations between the two countries and progress on North Korean denuclearization," White House press secretary Sarah Sanders said in a statement.

Their meeting Friday came shortly after Kim Yong Chol wrapped up talks with Secretary of State Mike Pompeo at a Washingotn hotel aimed at jump-starting the high-stakes nuclear negotiations that have been stalled for months over a U.S. demand that North Korea provide a detailed inventory of its nuclear and missile programs.

Pyongyang has insisted that the United States lift economic sanctions on North Korea and offer a security guarantee to the isolated regime before any further concessions.

With little progress on the technical end of the negotiations among lower-ranking diplomats, the fate of the talks may rely on Trump changing the current trajectory of the talks in interactions with senior North Korean officials.

U.S. officials want the North to start treating the American envoy for the talks, Steve Biegun, seriously. The North has repeatedly turned down meetings between him and his counterpart, Vice Foreign Minister Choi Sun Hee. If the talks go well on Friday, Biegun is expected meet his counterpart for follow on negotiations in Stockholm over the weekend.

Trump has been upbeat about a second round of face-to-face negotiations with Kim, touting personal letters from the North Korean leader as progress, despite a lack of measurable steps toward disarmament.

"With North Korea, we have a very good dialogue," Trump said Jan. 6. "I'm going to not go any further than that. I'm just going to say it's very special. And anybody else but me, you'd be in war right now."

The summit would probably take place in March or April, with Danang, Vietnam, seeming to be the most likely venue, according to people familiar with the negotiations.

In Seoul, there is a strong feeling that the U.S. side will come to the table offering a more flexible approach than before and that Washington is coming around to the idea that both sides need to offer concessions in a phased process, otherwise this simply isn't going to work.

South Korea's Foreign Minister Kang Kyung-wha told a news conference Wednesday that her government's approach is to secure a "comprehensive deal toward complete denuclearization" of the North and a "phased implementation." She said Washington "also shares considerably" this approach.

Kim Jong Un said in a New Year's Day speech that the North Korea might be forced to follow a new path if the United States maintains sanctions and demands unilateral action from Pyongyang. But Kim also said the improvement in relations could accelerate if the United States takes "corresponding actions."

Kim also told South Korean President Moon Jae-in last year he was prepared to permanently close the Yongbyon nuclear processing site if the United States takes "corresponding steps."

The question is what the United States is prepared to offer.

"Between South Korea and the United States, we are closely consulting what kinds of denuclearization measures should be followed and what the United States and the international community can do as corresponding measures," Kang said.

Corresponding measures could include a declaration to end the 1950-53 Korean War, humanitarian aid or a "permanent North-U. S. dialogue channel," said Kang. (One suggestion is that the two countries open liaison offices in each other's capitals.)

"There have been various discussions on corresponding measures, but ultimately, it is something that the United States has to provide, and North Korea has to accept this," she added.

Obviously Kim has demanded sanctions relief. One approach could be to suspend or partially roll back some of the sanctions that were imposed by the UNSC in 2017 in return for North Korea steps to denuclearize. Another would be to grant exemptions for specific projects: Moon's government is hoping to build road and rail links between the two Koreas, and also wants work to resume at a shuttered joint economic zone at Kaesong and a joint tourism project at Mount Kumgang in the North.

In terms of what North Korea is prepared to offer: Kim has made it clear he doesn't want to provide a list of nuclear and missile sites, because he thinks that is tantamount to providing a list of targets. Some people think this is unacceptable, and that the U.S./ROK should maintain this demand. Others are trying to find ways around it.

First, most people say, it is important to get North Korea to commit to a definition of what the "complete denuclearization of the Korean Peninsula" means, and agree to a detailed road map of how to get there.

A road map might, for example, mean starting by dismantling facilities that allow North Korea to expand its stock of fissile material and nuclear weapons in the future (such as Yongbyon as well as testing sites), before later steps whereby existing stocks of fissile material and ultimately weapons are dismantled at later dates, in return for phased concessions.

South Korean ruling party lawmaker Lee soo-hyuck, who led South Korea's negotiations with the North a decade and a half ago, said he met Stephen Biegun last December, and proposed such a road map. He says Biegun told him the U.S. proposed road map is "almost the same."

But there is real concern also that Moon and Trump have not asked Kim to spell out exactly what he means by denuclearization and whether he is ultimately demanding the United States withdraw its forces from South Korea and nuclear-armed submarines and bombers from the region. If so, they are dodging a key question that gets to the heart of whether a deal is even possible, experts say.

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Denyer reported from Tokyo.