“I’m not in a rush. I don’t want to rush anybody,” President Donald Trump said as he got ready to meet North Korea’s Kim Jong Un in Hanoi. Complete verifiable irreversible denuclearization had been the goal. But for now, “I just don’t want testing,” Trump said. “As long as there’s no testing, we’re happy.”

Kim took that view to heart and had a message of his own for Trump: new tests might well be in the offing, but with a tricky nuance or two that could leave POTUS off balance.

Satellite imagery by two independent groups of analysts—one at the Center for Strategic and International Studies’ Beyond Parallel program and the other at 38 North—shows that in the weeks leading up to the Kim-Trump summit in Hanoi, North Korea began putting back together at least two structures it had dismantled in 2018.

It’s unclear if there was a specific moment in U.S.-North Korea diplomacy that sparked Kim’s decision, but it appears to have occurred in early February after the first round of working-level talks between U.S. Special Representative for North Korea Stephen E. Biegun and his North Korean counterpart Kim Hyok Chol.

Both the structures are at a site known variously as Tongchang-ri, Sohae, or Yunsong. One structure that has been put back together is the static test stand where North Korea tested its most advanced liquid propellant engines in 2016 and 2017—the ones that found themselves powering its largest intercontinental-range ballistic missiles in July and November 2017.

Not far from that test stand is the Sohae Satellite Launch Facility—Pyongyang’s main satellite launch vehicle preparation and launch site since 2012. There, North Korea put back together a rail-mounted processing building. Basically, this is where North Korea would assemble a satellite launcher before it would be moved to the nearby gantry for a launch.

None of this is great news.

These facilities are ones that North Korea promised to dismantle under the September 19, 2018, inter-Korean Pyongyang Declaration in a process supposed to be under the observation of “experts.”

Kim Jong Un signed that document, and the reversal puts that agreement under stress.

South Korean President Moon Jae-in, already distressed by the negative outcome in Hanoi, will be more eager now than ever to help Washington agree to the terms for a deal that Pyongyang had offered in Hanoi—perhaps the point of this whole exercise.

But despite some reports that framed this activity as preparation for a “missile” launch, nothing could be further from the truth. North Korea has never launched a ballistic missile from Sohae; only satellite launch vehicles.

And despite U.S. Secretary of State Mike Pompeo’s exhortations after Iran’s recent satellite launches that these tests can help develop technologies seen in ICBMs, with North Korea that concern is less apparent.

Pyongyang already has conducted three tests of two separate ICBM designs, but its satellite designs in the past, too, would have made lousy missiles—capable of carrying just a tiny payload.

North Korea’s satellite launches work quite a bit differently than its missile launches, so it’s unlikely Trump will be interrupted by a sudden “North Korea launches missile” push-alert on his phone during “executive time.”

Pyongyang would provide a notification of a launch window: a period of time in which a launch might take place. That would be accompanied by a “notice to airmen” outlining the coordinates where a satellite’s spent stages would drop.

In 2012, the Obama administration’s February 29 “Leap Day Agreement” with North Korea quickly fell apart after precisely such a North Korean notification of a plan to launch a satellite.

At the time, the U.S. and North Korean sides had left negotiations without an agreed statement—much like Hanoi—but each side noted its understanding of what had been agreed between them. It turned out that the U.S. side saw satellite launch vehicles as being covered under the missile-testing moratorium North Korea had agreed to. Pyongyang didn’t share that view and the whole thing collapsed.

Similarly, in Hanoi, Trump confirmed at a press conference that Kim had told him there’d be no missile or nuclear tests. But did the president ask his “friend” Kim if that meant space launches were also out of the question?

We’re not at the point yet where, based on the evidence, we ought to worry about an imminent North Korean satellite launch—or any other provocative activity. But the possibility shouldn’t be written off.

Toward the end of 2017, some evidence emerged that North Korea’s National Aerospace Development Administration (NADA), its civilian space agency, had been working on new satellite launch vehicle designs. Additionally, while the September 2018 military parade in Pyongyang excluded all ballistic missiles as diplomacy was ongoing with South Korea and the United States, it did feature a float prominently underscoring space exploration. (The float did not show an actual satellite launch vehicle, however.)

North Korean state media’s positive coverage of the Hanoi summit suggests that for now Pyongyang is content to work toward a third summit at some point in the future, but it wants Washington to take its negotiating positions seriously in the interim.

Trump—always so concerned about testing and launches in North Korea—perhaps missed a similar signal last year.

In November 2018, Kim oversaw the test of what the country’s state media called an “ultramodern tactical weapon.” The weapon wasn’t shown and coverage of the event was modest in the United States. By all accounts, it did little to shift the administration’s thinking on what might happen if diplomacy were to hit a wall.

This time, the signs are more apparent. Cable news—the president’s intelligence source of choice—has been all over recent reports about the reconstitution of these facilities. President Trump has set aside concern for now, noting that he would be “very disappointed” if the reports were true. Given that all this was well underway before the meeting in Hanoi, it’s more likely than not that the president knew about this from his pre-summit briefing.

In the end, the new activity at Sohae serves as a warning to Trump and reminder of what stands to be lost if this process were to collapse. Kim Jong Un warned during his New Year’s Day address that Washington should not test his “patience” and demand North Korea’s unilateral disarmament—which is exactly what happened in Hanoi.

Consider the work at Sohae a way for Kim to convert that same warning from words to satellite images. Before a third summit, Trump might finally get what North Korea is trying to say.