North Korea is rapidly moving the goal posts for next month’s summit between leader Kim Jong Un and President Trump, saying the United States must stop insisting that the North “unilaterally” abandon its nuclear weapons program and stop talking about a Libya-style solution to the standoff.

The latest warning, delivered by former North Korean nuclear negotiator Kim Gye Gwan on Wednesday, fits Pyongyang’s well-established pattern of raising the stakes in negotiations by threatening to walk out if it doesn’t get its way.

This comes just hours after the North Korean regime cast doubt on the planned summit by protesting joint air force drills taking place in South Korea, saying they were ruining the diplomatic mood.

If the Trump administration approaches the summit “with sincerity” for improved relations, “it will receive a deserved response from us,” Kim Gye Gwan, now vice foreign minister, said in a statement carried Wednesday by the North’s official Korean Central News Agency (KCNA).

“However, if the U.S. is trying to drive us into a corner to force our unilateral nuclear abandonment, we will no longer be interested in such dialogue and cannot but reconsider our proceeding to the DPRK-U.S. summit,” he said, using the abbreviation for North Korea’s official name. He also questioned the sequencing of denuclearization first, compensation second.

Analysts said they were not surprised by these latest developments in what has been a year of diplomatic whiplash.

“The U.S. and South Korea hold an exercise, which contains some strategic strike elements to it. U.S. officials can’t seem to get on the same page regarding denuclearization and what is required of North Korea,” said Ken Gause, a North Korea leadership expert at CNA, a Virginia-based consulting firm. “At some point, North Korea was going to cry foul.”

Trump and Kim Jong Un are due to meet in Singapore on June 12, which would be the first meeting between a North Korean leader and a sitting U.S. president.

Trump and his top aides, including Secretary of State Mike Pompeo and national security adviser John Bolton, have repeatedly said the United States wants the “complete verifiable irreversible denuclearization of North Korea” — a high standard that Pyongyang has previously resisted.

Bolton, known for his sharply hawkish views, has said that North Korea must commit to a disarmament similar to “Libya 2004.” He was undersecretary of state for arms control in 2004, when Libyan leader Moammar Gaddafi agreed to give up his nuclear program in return for sanctions relief.

But this is not a tempting model for North Korea. Seven years after surrendering his nuclear program, Gaddafi was overthrown, then brutally killed, by opponents of his regime.

North Korea lashed out at Bolton, whom the regime derided as “human scum” when he worked in the George W. Bush administration, and at the suggestions that North Korea should be dealt with in the same way that the Bush administration dealt with Libya and Iraq.

“This is not an expression of intention to address the issue through dialogue. It is essentially a manifestation of awfully sinister move[s] to impose on our dignified state the destiny of Libya or Iraq, which had been collapsed due to the yielding of their countries to big powers,” Kim Gye Gwan said.

The “world knows too well that our country is neither Libya nor Iraq, which have met a miserable fate,” Kim Gye Gwan said, harking back to North Korea’s previous criticism of Bolton. “We shed light on the quality of Bolton already in the past, and we do not hide a feeling of repugnance toward him,” the vice minister said.

In negotiations over the years, North Korea has repeatedly threatened to walk out over disagreements — and has on occasion actually walked out. In that respect, Wednesday’s announcement is not surprising and underscores analysts’ warnings that North Korea will not give up its nuclear weapons easily.

During the April 27 inter-Korean summit, Kim Jong Un and South Korean President Moon Jae-in agreed to work toward the “complete denuclearization of the Korean Peninsula,” phrasing that was seen as code for mutual arms reduction.

Earlier Wednesday, KCNA protested the joint U.S.-South Korea military exercises taking place in the southern half of the peninsula, threatening to pull out of the summit over this “provocation.”

North Korea said barely a word about the drills during computer simulation exercises that took place through April, and the South Korean and U.S. militaries had scaled back and played down the exercises to avoid antagonizing the North.

But the two-week-long Max Thunder drills between the two countries’ air forces, an annual event that began Friday and involves about 100 warplanes, including B-52 bombers and F-15K jets, have clearly struck a nerve.

“The United States will also have to undertake careful deliberations about the fate of the planned North Korea-U.S. summit in light of this provocative military ruckus jointly conducted with the South Korean authorities,” the KCNA report said.

Max Thunder has been held annually in the spring for about 10 years. It features the United States and South Korea flying strike aircraft together from air bases in South Korea and Japan to practice air-to-air combat. About 1,000 U.S. troops and 500 South Koreans were involved last year, according to a U.S. military statement published at the time.

South Korea’s Defense Ministry said the Max Thunder drills would carry on as planned and that there is no disagreement on this between South Korea and the United States.

“The Max Thunder drill is training for pilot skill enhancement, not an attack drill or implementation of an operation plan,” Defense Ministry spokeswoman Choi Hyun-soo said.

A Pentagon spokesman, Army Col. Robert Manning III, said Tuesday that the exercises are part of the U.S.-South Korean alliance’s “routine, annual training program to maintain a foundation of military readiness.”

Manning said the purpose of the exercises is to enhance the alliance’s ability to defend South Korea. “While we will not discuss specifics, the defensive nature of these combined exercises has been clear for many decades and has not changed,” he said.

North Korea, as it has in the past, disagreed. “This exercise targeting us, which is being carried out across South Korea, is a flagrant challenge to the Panmunjom Declaration and an intentional military provocation running counter to the positive political development on the Korean Peninsula,” KCNA said.

By mentioning the Panmunjom Declaration, North Korea was referring to the agreement signed last month by Kim and Moon following their historic summit.

They agreed to work to turn the armistice agreement that ended the Korean War in 1953 into a peace treaty that would officially bring the war to a close, and to pursue the “complete denuclearization” of the Korean Peninsula.

Trump administration officials said they were continuing to work toward the June 12 summit between Trump and Kim.

“The United States will look at what North Korea has said independently and continue to coordinate closely with our allies,” said White House press secretary Sarah Huckabee Sanders.

State Department spokeswoman Heather Nauert said the United States has not received notice of any change or cancellation. She said the government is continuing to plan for the summit and is confident that Kim understands the need for the exercises.

At the same time as it threatened to scuttle the summit with Trump, North Korea canceled talks with South Korean officials that had been scheduled for Wednesday, less than 24 hours after agreeing to them.

North Korea had said it would send five senior officials to the border village of Panmunjom for meetings with South Korean officials, the first such talks since the April 27 inter-Korean summit.

They were due to discuss some of the infrastructure aid that South Korea would provide to North Korea as part of their broader detente. The North was going to send Ri Son Kwon, who leads the North Korean agency in charge of inter-Korean exchanges and was present at the summit, while the South was going to send senior officials from the Transport Ministry and forest service.

Min Joo Kim in Seoul and Dan Lamothe and Anne Gearan in Washington contributed to this article.