President Trump and Kim Jong Un could meet by the end of May. (AP)

North Korea has confirmed directly to the Trump administration that it is willing to negotiate with the United States about potential denuclearization, administration officials said Sunday, a signal that the two sides have opened communications ahead of a potential summit between President Trump and Kim Jong Un next month.

The message from Pyongyang offers the first reassurance that Kim is committed to meeting Trump. The U.S. president accepted an offer made in March on Kim’s behalf by South Korean emissaries during a meeting at the White House, but Pyongyang had not publicly commented.

“The U.S. has confirmed that Kim Jong Un is willing to discuss the denuclearization of the Korean Peninsula,” said a senior administration official, who was not authorized to speak on the record. A second official also confirmed that representatives of North Korea had delivered a direct message to the United States, which was first reported by the Wall Street Journal.

At the same time, U.S. officials cautioned that Pyongyang offered no details about its negotiating position and noted that North Korea has violated past agreements, during the George W. Bush administration, to freeze its nuclear weapons and ballistic missile programs.

Foreign policy analysts warned that the Kim regime has long defined the concept of denuclearization differently than the United States has, seeking the removal of U.S. troops from the Korean Peninsula and an agreement that the United States will no longer protect allies South Korea and Japan with its nuclear arsenal. Previous U.S. administrations have unilaterally rejected such demands.

“It means the removal of the threat posed by us, not them,” said Evans Revere, an Asia analyst at Albright Stonebridge Group who was a high-ranking State Department official before retiring in 2007. “It’s been defined as this for us on many occasions. My conclusion is this is not new. Various outlets are describing this as a major breakthrough on North Korea’s commitment toward denuclearization. It’s no such thing.”

Despite such cautionary notes, Trump surprised his aides last month when he accepted the offer from Kim during the meeting with the South Koreans and instructed his aides to arrange it before the end of May.

The move came after months of bellicose threats between Trump and Kim, during which North Korea conducted several nuclear and ballistic missile tests, showing a significant advancement in its military capabilities.

South Korean officials used their country’s hosting of the Winter Olympics to help open a dialogue with Pyongyang, leading to the diplomatic efforts to lessen tensions. And Kim visited Beijing this month in his first trip outside North Korea since he assumed control of the country after his father, Kim Jong Il, died in 2011.

Japanese Prime Minister Shinzo Abe is scheduled for a two-day visit with Trump this month at Mar-a-Lago, the president’s resort near Palm Beach, Fla., to coordinate strategy between the allies. South Korean President Moon Jae-in plans to meet with Kim at the end of the month in the demilitarized zone between the North and the South.

White House officials have not said where the Trump-Kim summit will be held. The agenda of the meeting is not yet known, and North Korea has not been clear about what steps it is willing to take to move toward denuclearization. White House officials have vowed to maintain tough economic sanctions imposed on Pyongyang over the past year by the United States and the United Nations.

During previous negotiations under different U.S. administrations, the North has agreed to freeze its nuclear weapons program in exchange for the lifting of international economic sanctions, only to violate the agreement by testing more weapons.

Christopher R. Hill, a former State Department official who led the U.S. delegation in the “six-party talks” with the North during the Bush era, said the North Koreans are sophisticated negotiators who know what the United States wants.

“The question is when and how and what they want in return for it,” Hill said. “If the notion is denuclearization where you take all the forces that threaten them off the Korean Peninsula, it’s not going to work. . . . If they have in mind the sorts of things on offer in 2005 — energy assistance, economic assistance, cross recognition of states, a peace treaty — we’re in business. But at this point, we just don’t know.”

Trump administration officials declined to disclose how the North Koreans delivered their direct message. The United States does not have diplomatic relations with Pyongyang, and Joseph Yun, the State Department’s special representative on North Korean policy, retired in February.

But the North does have diplomats at the United Nations in New York, and U.S. intelligence officials have reportedly been in contact with North Korean emissaries. Although allowing intelligence agencies to take the lead in summit planning is an un­or­tho­dox approach, Trump has nominated CIA Director Mike Pompeo to replace Rex Tillerson, who was fired last month as secretary of state.

Pompeo, a former congressman who has gained Trump’s trust by delivering his daily intelligence briefing, has taken a hard-line stance on North Korea, as has John Bolton, who has formally replaced H.R. McMaster as Trump’s national security adviser.

It is not known whether the Senate will be able to vote before the summit on whether to confirm Pompeo as secretary of state.

Trump administration officials said that a “comprehensive, whole-of-government effort” is underway to prepare for the North Korea talks, with National Security Council aides coordinating policy between key government agencies, including the State Department, the Pentagon and the Treasury Department.

But it remains unclear how many direct talks between U.S. and North Korean officials will take place before a potential leaders’ meeting. Traditionally, U.S. diplomats would meet with their counterparts from another country ahead of time to negotiate where such a meeting would take place and the agenda, as well as certain agreements or joint statements that could be made during the summit.

Without such planning meetings, it is difficult to envision what Trump intends to achieve.

On the key question of whether Kim is truly willing to give up his nuclear program, experts said it remains a long shot.

“Think of it from North Korea’s point of view — what assurances, verbal or written, could the U.S. provide that in their mind would give them greater security assurances than the possession of nuclear weapons?” said Bruce Klingner, an Asia expert at the conservative Heritage Foundation who served as the CIA’s deputy division chief for Korea from 1996 to 2001.

Trump aides have said time is fast running out to change North Korea’s strategy and its trajectory on nuclear weapons. Tests last year showed that the North appears to have achieved the ability to strike the U.S. mainland with a ballistic missile. The Kim regime could be only months away from being able to mount a nuclear warhead on such missiles, which Trump has called a game-changer.

Aides point to failed diplomatic talks at lower levels for the past 27 years as evidence that something more dramatic is required to achieve a breakthrough. Still, experts remain skeptical.

“I’m an advocate for high-level talks with North Korea, but I’m not supportive of this presidential summit for a lot of reasons,” said Revere, the former State Department official, “not the least of which is that this is not a serious and sincere and potentially productive North Korean offer.”

John Hudson contributed to this report.