U.S. President Donald Trump took to Twitter on Sunday to serve up the dubious claim that North Korea has “agreed to denuclearization” ahead of his meeting with Kim Jong Un — an assertion at odds with what the White House has previously said and something Pyongyang has yet to say publicly.

Kim announced over the weekend that his country had suspended nuclear and longer-range missile tests and shut down its main atomic test site, saying that it would now shift its focus to shoring up its sanctions-hit economy.

There was no mention of it relinquishing its nuclear arsenal.

Instead, Kim called the country’s rapid progress in its state nuclear program a “great victory” that had created a “climate of detente and peace” on the Korean Peninsula and the region.

“Dramatic changes are being made in the international political landscape,” Kim said.

Despite the conspicuous absence of any language signaling that it might accede to U.S. demands to give up its nukes, Trump tweeted that the North has “agreed to denuclearization (so great for World), site closure, & no more testing!”

Twelve minutes later, the U.S. leader followed that tweet with another appearing soften the tone of his earlier message.

“….We are a long way from conclusion on North Korea, maybe things will work out, and maybe they won’t- only time will tell….But the work I am doing now should have been done a long time ago!” he wrote.

The U.S. acknowledged earlier this month that the North said it is ready to discuss the denuclearization issue, but experts and observers say it is extremely unlikely that Pyongyang would give up its “treasured sword” in the near-term, even with significant inducements.

“Kim’s speech before the Korean Workers’ Party read like a consolidation or consummation of his regime’s status as a nuclear state,” said Van Jackson, a North Korea expert and former policy adviser in the U.S. Office of the Secretary of Defense. “They were chasing it all along, they achieved it by Nov. 28 last year, and now he’s ready to move on. There was no hint of denuclearization in Kim’s speech.”

Pyongyang conducted its sixth and most powerful nuclear test last year and launched more than 20 missiles — including two intermediate-range weapons that flew over Japan and another long-range missile that experts say puts the whole of the United States in striking distance. With the test of that long-range missile in November, the North said it had “realized the great historic cause of completing the state nuclear force.”

The North Korean nuclear issue is Trump’s top foreign policy challenge, and media reports quoting White House insiders have said he hopes to write his name in the history books by clinching a historic deal with the regime.

But his belief that he can quickly reach an agreement — and what exactly that deal might mean — highlights a potentially dangerous perception gap between the two countries.

“Trump either believes that North Korea has agreed to unilateral denuclearization, which it hasn’t, or he is intentionally obfuscating on what ‘denuclearization of the Korean Peninsula’ means in order to get a short term diplomatic win,” said Vipin Narang, a professor of international relations at MIT. “Neither are good news.”

Narang said one scenario could result in “a big surprise when Kim says ‘you first’ ” in regards to denuclearizing, while the other “just kicks this whole can down the road for a nice photo op which may temporarily sideline the issue politically but which achieves little substantively.”

In a stunning turn of events after months of acrimony — including threats by Trump of “fire and fury” and insults from Kim calling the American leader a “mentally deranged … dotard” — Trump accepted an invitation from Kim last month to meet at an undetermined time and location.

North and South Korea, meanwhile, are in the final stages of preparations for a summit between Kim and South Korean President Moon Jae-in at the border truce village of Panmunjom on Friday.

While a venue and time have yet to be set for the Kim-Trump meeting, the planned talks gained steam recently when Trump said that his pick to be the next secretary of state, CIA Director Mike Pompeo, had traveled to North Korea to meet Kim over Easter weekend to lay the groundwork for the summit.

On Sunday, The Wall Street Journal reported that Kim had asked Pompeo to agree to a “phased” approach to the North’s denuclearization, a proposal that would likely take years to realize.

But the Trump administration is wary of agreeing to that, and instead is pushing for a “big bang” approach involving major concessions at an early juncture, the Journal said, quoting a person familiar with the matter.

The paper quoted a senior Trump administration official as saying that the president plans to tell Kim that sanctions will not be withdrawn until North Korea has “substantially dismantled its nuclear programs.”

Kim mentioned a “phased, synchronized” approach to denuclearization at his meeting with Chinese President Xi Jinping in Beijing last month, according to the Chinese government.

Through such a plan, North Korea likely seeks to secure rewards such as the easing of sanctions or the provision of economic aid in exchange for incremental steps toward giving up its nuclear arsenal.

Asked about U.S. views on North Korean denuclearization, White House Legislative Affairs Director Marc Short said in an interview Sunday on NBC’s “Meet the Press” that there needs to be “a sit-down conversation to get to that point.”

“But I think from our perspective, it means full denuclearization,” he said. “No longer having nuclear weapons that can be used in warfare against any of our allies.”

Short described the Trump administration’s view on North Korea as one of “cautious optimism.”

But the president has been far from cautious with his tweets and pronouncements, said Jackson.

“Negotiating 101 is to set in-going expectations low, and Trump’s been doing the opposite of that by claiming Kim agreed to things he obviously hasn’t agreed to and wouldn’t ever agree to,” Jackson said. “Aside from sabotaging negotiations, it’s a bit own-goal with Japan.”