Top North Korean officials have discussed the country’s intention to deceive the U.S. about the number of nuclear warheads in its possession, including a strategy to potentially declare they have denuclearized after disposing of 20 weapons while retaining dozens more, according to a report by The Washington Post.

Monday’s report, citing intelligence gathered by U.S. spy agencies and unidentified officials, also said there were signs that North Korea is continuing to construct at least one, and possibly two, liquid-fueled intercontinental ballistic missiles (ICBMs) capable of reaching the United States.

The findings, including satellite photos taken in recent weeks, indicated that the work was under way at the same factory that produced the country’s first large ICBM, the Hwasong-15, in Sanumdong, on the outskirts of Pyongyang, according to the report. It said that imagery collected by the National Geospatial-Intelligence Agency in recent weeks also pointed to “ongoing work on at least one Hwasong-15” at the Sanumdong site.

“We see them going to work, just as before,” the Post quoted one U.S. official as saying.

Asked about the report, the Pentagon declined to comment.

While the intelligence does not suggest an expansion of North Korea’s capabilities, the findings are the latest to show ongoing activity inside its nuclear and missile facilities at a time when the country’s leaders are engaged in arms talks with the United States.

It also comes despite U.S. President Donald Trump’s claim on Twitter, shortly after his landmark summit with North Korean leader Kim Jong Un in Singapore, that Pyongyang was “no longer a Nuclear Threat.”

Earlier this month, media reports revealed that the North was secretly operating a suspected uranium enrichment facility, called Kangson. U.S. Secretary of State Mike Pompeo acknowledged during Senate testimony last week that North Korean factories “continue to produce fissile material” used in making nuclear weapons. He declined to say whether Pyongyang is constructing new missiles.

At the Singapore summit in June, Kim agreed in a vaguely worded joint statement to “work toward” the “denuclearization” of the Korean Peninsula. Since then, the North has made few tangible moves that would signal it intends to relinquish its nuclear weapons — with the exception of the ongoing dismantlement of the Sohae missile engine test-stand, which some experts say is both unneeded by the regime and reversible.

Instead, the Post reported that “senior North Korean officials have discussed their intention to deceive Washington about the number of nuclear warheads and missiles they have, as well as the types and numbers of facilities, and to rebuff international inspectors, according to intelligence gathered by U.S. agencies.”

Their strategy, the Post said, “includes potentially asserting that they have fully denuclearized by declaring and disposing of 20 warheads while retaining dozens more.”

In a report dated July 28, 2017, the U.S. Defense Intelligence Agency estimated that the North possesses as many as 60 nuclear weapons, but Monday’s report said that intelligence agencies had in recent months increased their estimates of the size of the arsenal, taking into account enriched uranium from at least one secret enrichment site.

After racing toward his goal of developing a nuclear-tipped missile capable of striking the continental United States, Kim said in April that he had shifted his country’s focus to the economy.

But some experts remain skeptical, claiming that Kim had already conveyed his true intentions during his annual New Year’s speech in January. In that address, the North Korean leader was unequivocal about what was next, they say.

“The nuclear weapons research sector and the rocket industry should mass-produce nuclear warheads and ballistic missiles, the power and reliability of which have already been proved to the full, to give a spur to the efforts for deploying them for action,” Kim said at the time.

Vipin Narang, a North Korea expert and professor of international relations at MIT, noted that this was also clear from the Kim-Trump summit.

“In Singapore I never heard the words: we will unilaterally disarm,” Narang said. “So between this and Kangson, we are seeing an expanded and improved nuclear and missile force.”

But Narang said the most interesting revelation was not that the North was continuing to build its nuclear forces, but rather the apparent strategy of deception.

“Offer up 20 first-gen warheads, claim you are or have disarmed, but keep the good stuff in presumably clandestine facilities and hope they aren’t discovered,” Narang said. “But even if they are, you still have a nuclear deterrent, so it would still be a huge risk for the U.S. to try to attack.”

Narang said the aim of such a strategy would be to obtain sanctions relief, while still retaining a deterrent — what he called “the best of all worlds for North Korea.”

“That’s why the first step the intelligence community is probably looking for is a complete declaration of nuclear and missile related facilities — to see if North Korea includes everything they already know about or suspect,” he said.

The U.S., he added, has “to know what they have before talking about caps and arms control.”

Still, Joel Wit, a former State Department negotiator and founder of North Korea-watching website 38 North, said that the North’s moves were, historically, par for the course.

“Until the ink is dry on an agreement it’s unrealistic to expect the DPRK to stop its programs,” Wit wrote on Twitter on Monday, using the acronym for North Korea’s formal name. “That was certainly the case during the Cold War when the U.S. and USSR continued to build missiles and nuclear weapons even while negotiating arms reduction agreements.”