TOKYO — President Trump may have fallen “in love” with his North Korean counterpart, Kim Jong Un, but Pyongyang wants Washington to prove its affection — by lifting sanctions.

As Secretary of State Mike Pompeo plans to head to Pyongyang this weekend to prepare the ground for a second Trump-Kim summit, North Korea appears to have upped its demands, arguing that the United States should show that it is serious about dialogue by easing sanctions, before North Korea takes steps to denuclearize.

After a summit between the leaders of the two Koreas last month, Kim said he was prepared to permanently dismantle his country’s main nuclear site, but only if the United States took “corresponding steps” to build trust.

At the time, it appeared that meant a declaration to formally end the 1950-53 Korean War, as a signal that hostilities between the two countries were over. But during the past few days, Pyongyang has signaled that it may want more than that to move forward.

A declaration to end the war should have come half a century ago, after the warring parties signed an armistice agreement, the Korean Central News Agency wrote in a commentary on Tuesday. “It can never be a bargaining chip for getting the DPRK denuclearized.”

North Korea refers to itself as the Democratic People’s Republic of Korea (DPRK).

By contrast, the Yongbyon facility is a “core” part of the country’s nuclear program, KCNA argued. It is the site of the country’s only nuclear reactor, producing plutonium that can be used in nuclear weapons, but also is believed to house a separate uranium enrichment facility.

“The KCNA commentary shows that North Korea is constantly raising their demands,” said Woo Jung-yeop, a researcher at South Korea’s Sejong Institute.

North Korean Foreign Minister Ri Yong Ho delivered a similarly combative message at the U.N. General Assembly on Saturday. 

“The perception that sanctions can bring us on our knees is a pipe dream of those who are ignorant about us,” he said. “But the problem is that the continued sanctions are deepening our mistrust.”

He added: “Without any trust in the U.S., there will be no confidence in our national security, and under such circumstances there is no way we will unilaterally disarm ourselves first.”

Rodong Sinmun, the official newspaper of the Workers’ Party of Korea, underlined the point in an editorial Sunday.

“Sanctions and dialogue can never go together,” it said. “It is a contradiction that the U.S. is talking about the dialogue with its partner while ratcheting up sanctions and pressure on it. The U.S. should squarely see the trend of the times and make a proper choice.”

The United States argues that the sanctions should remain in place until North Korea has fully and verifiably denuclearized.

Vipin Narang, an associate professor of political science at the Massachusetts Institute of Technology, said the comments “really [put] a little bit of cold water” on the hope that North Korea might provide a list of its nuclear and missile sites in return for an end-of-war declaration.

To build trust, North Korea appears to want “a transformation of the relationship, and the first step of that would have to be comprehensive sanctions relief,” he said.

Experts say Pyongyang is not ready to offer a comprehensive list of its nuclear facilities, believing this would either be disbelieved or give the United States a list of future military targets. 

Instead, it wants to take things at its own pace, offering up Yongbyon as part of a phased process in which both sides take steps to build trust.

The offer to close Yongbyon “doesn’t get at the heart of their program. But it’s a good first step,” said Joel Wit, a senior fellow at the Stimson Center in Washington who was involved in past negotiations with the North Koreans while working at the State Department. “Knowing the North Koreans, I think they have other things up their sleeve that they are willing to do.”

Experts differ about North Korea’s sincerity: Some, like Narang, say it has no real interest in disarmament and is just milking the process for whatever benefits it can get. 

Others say Pyongyang may be prepared to reduce — but not eliminate — its nuclear stockpile and missile capability, in return for economic benefits and security guarantees from Washington.

The South Korean government and some experts go further, arguing that Kim may be prepared to completely denuclearize — under the right circumstances.

Even some skeptics, though, acknowledge that the current dialogue has brought rewards in terms of an end to nuclear and missile testing and reduced tensions.

The question is how long that process can be sustained, and how it will end: with a nuclear-free North Korea at peace with its neighbors, with detente and containment of a de facto nuclear-armed state, or with a return to open hostility.

For now, Pompeo may explore how serious North Korea is in its offer to dismantle Yongbyon and what it wants in return, and then decide whether that represents a sound basis for another meeting between Trump and Kim, something both leaders appear eager to make happen.

South Korea’s presidential Blue House has been arguing for an end-of-war declaration and predicts that such a declaration could come after Trump and Kim meet again.

A senior Blue House official, speaking on the condition of anonymity to discuss sensitive issues, told reporters Wednesday that Seoul had initially thought that a Trump-Kim summit might happen after the U.S. midterm elections on Nov. 6, but the fact that Pompeo is visiting Pyongyang sooner than expected “sends a positive signal” that it might take place earlier.

At a campaign rally Saturday, Trump said he and Kim “fell in love,” adding, “He wrote me beautiful letters.”

Pompeo, on his fifth visit to Pyongyang this year, is expected to meet Kim on Sunday, which experts said would be a positive sign. He begins his trip in Tokyo and will also visit Seoul and Beijing.

Obviously, these conversations are going in the right direction, and we feel confident enough to hop on a plane to head there,” State Department spokeswoman Heather Nauert said Tuesday.