By Abigail Abrams
February 26, 2019

After a summit in Singapore with North Korean dictator Kim Jong Un last summer, President Donald Trump tweeted that “there is no longer a nuclear threat from North Korea.”

The enthusiasm proved premature.

Diplomatic progress between the two countries slowed throughout the fall, and North Korea continued many of its activities as usual, including advancing its nuclear weapons research and improving some missile bases, according to experts.

As he heads to a second summit in Vietnam this week, Trump has continued to lavish praise on Kim, but he has dialed down some of the claims. Other U.S. officials, including Secretary of State Mike Pompeo, have said they hope to achieve more “real demonstrable, verifiable” steps this time around.

Here’s a closer look at the evidence that North Korea has not significantly changed its nuclear weapons program since the summit in Singapore.

North Korea’s first steps weren’t significant

Over the course of 2018, North Korea did make a few big gestures at limiting its nuclear weapons program. But many of these took place in preparation for Kim’s first meeting with Trump.

In late April, Kim announced he would suspend nuclear and missile tests and close a nuclear test site at Punggye-ri — but he said he was doing so simply because North Korea no longer needed to test nuclear weapons or intercontinental missiles.

Then when North Korea said it destroyed the nuclear test site in May, it allowed foreign journalists to observe explosions set off at the site’s entrances, but did not let nuclear experts verify that the site was fully destroyed.

“Trump has held up the testing moratorium and North Korea’s partial dismantlement of a missile test site as significant steps,” says Kelsey Davenport, director of nonproliferation policy at the Arms Control Association. “But in reality, these are low-cost commitments for North Korea to make and these steps do not reduce the risk posed by the nuclear weapons program. And they don’t indicate if North Korea is serious about pursuing denuclearization.”

North Korea is still making fuel for nuclear weapons

Soon after Trump and Kim met in Singapore, analysts began to raise questions about how much progress was really being made.

Few expected North Korea to make drastic changes right away, but it soon became clear that many aspects of the country’s nuclear weapons program were running business as usual. In July of 2018, for example, Pompeo drew headlines when he told the Senate Foreign Relations Committee that North Korea was actively make fuel for nuclear weapons, saying “they continue to produce fissile material.”

North Korea likely added several nuclear bombs to its arsenal last year, according to experts. Some estimates have said the regime had enough fissile material for about six additional nuclear weapons, which would mean it has 30 to 60 in total.

“North Korea set the goal in 2018 of mass production of nuclear weapons,” Davenport said. “So North Korea’s arsenal continues to grow as diplomacy progresses.”

The U.S. doesn’t know a lot of details about the program

There were also reports that North Korea was not only continuing its previous efforts, but also increasing production of fuel in 2018. In late June, NBC News reported that U.S. intelligence agencies believed North Korea was ramping up production at undeclared sites. That same month, intelligence officials told the Washington Post that they believed that Pyongyang was planning to deceive Washington about the number of missiles, nuclear warheads and facilities they have.

From the beginning, the U.S. wanted North Korea to provide a comprehensive list of its nuclear weapons and missile sites so the two sides would be operating with the same information. But Kim refused to disclose this information, which left many wondering how much of North Korea’s nuclear operation the U.S. did not know about.

After North Korea postponed a meeting with Pompeo in November, Vice President Mike Pence said the U.S. would not require North Korea to provide a complete list of its nuclear assets before a second summit.

This lack of knowledge was highlighted by the International Atomic Energy Agency last year. The group said in an August report that it remained unable to verify activities in North Korea, and warned that “knowledge of the DPRK’s nuclear program is limited and, as further nuclear activities take place in the country, this knowledge is declining.”

There is evidence that North Korea has expanded

As North Korea withheld information, a number of reports emerged throughout last year that showed missile bases continuing to operate and even expanding.

“Since the Singapore summit, North Korea has not taken any significant steps that either reduced the threat posed by its nuclear weapons program or rolled it back,” Davenport said.

Satellite images published in June by 38 North, a website dedicated to analyzing North Korea, showed that “improvements to the infrastructure” at North Korea’s Yongbyon Nuclear Scientific Research Center were “continuing at a rapid pace.”

Reports in July included satellite images showing North Korea was expanding a ballistic missile manufacturing site and may have been building new missiles at a facility in Sanumdong.

North Korea was also making improvements to 16 hidden missile bases, according to images first published in November by the New York Times. And in December, another report revealed that Kim’s regime had expanded an important long-range missile base.

Despite these frequent reports, many experts say the continued operations are less worrying than they might sound at first glance.

Read More: How the U.S. Could Lose a Trump-Kim Summit

“We have seen a lot of the sites that are often associated with the nuclear program have continued to operate. And we’ve also seen a couple of new sites be publicly revealed,” said Cristina Varriale, a research fellow focused on nuclear policy at the Royal United Services Institute think tank. “Just because a site was revealed publicly doesn’t mean they’re new or represent an expansion of the North Korean program.”

“While it’s not necessarily positive sign that some of these facilities have continued to operate, North Korea hasn’t yet agreed to stop any of these activities,” she continued.

Other experts agreed that while North Korea might not have taken significant steps toward denuclearization, it has not gone back on any agreements yet. U.S. officials went in to negotiations last year with high expectations and wanted North Korea to make big changes before they would offer any concessions, says Jenny Town, a research analyst at the Stimson Center and managing editor of 38 North.

“The only thing that came out of Singapore was they set an overall agenda of here are the aspirations we’re working toward,” Town said.

“The problem is that the U.S. is very impatient and they think that North Korea should just be willing to do these things to get in our good graces,” she added. “But there’s no country that’s ever been in arms control negotiations where — even if they have the political will to go into the negotiations — they unilaterally stop their program while they are negotiating.”

There are still hopes for more progress

In more recent months, both the U.S. and North Korea have seemed to make slightly more progress.

Kim’s domestic rhetoric has shifted somewhat, Town said, as he has told his own citizens about being open to denuclearization.

The U.S. has also appeared to soften its position, with both Pompeo and Stephen Biegun, the special representative for North Korea, indicating that they would consider offering some concessions earlier in the process if North Korea makes more concrete commitments too.

In remarks at Stanford last month, Biegun said the U.S. had communicated to North Korean officials that they were prepared to pursue commitments “simultaneously and in parallel” with Pyongyang.

Town and other experts said this will be critical to moving forward at the Hanoi summit this week.

“North Korea is never going to unilaterally give up their nuclear weapons as long as the political relationship with the United States stays the same,” she said. “Until there is an actual change in the nature of the relationship that helps justify them going down that path and there are some tangible benefits, that are not only promised but have started to be received, we’re not getting to the end of the road.”

Write to Abigail Abrams at abigail.abrams@time.com.

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