The collapse of the summit in Hanoi had a silver lining, the White House argued last week. Donald Trump and Kim Jong-un parted on friendly terms, which guaranteed a continued halt to missile and nuclear tests. That represented a significant security gain for the US from the two summits, which the administration traded off by ending large-scale military drills with South Korea.

That silver lining may have turned into a dark cloud after all. Two analyst groups report that North Korea has begun rapidly rebuilding one of its premier missile launch sites, a process that began shortly before or shortly after the Hanoi summit:

North Korea has begun rebuilding a satellite rocket launchpad and engine test site, in an ominous sign about its attitude toward negotiations on denuclearization.

The rebuilding work at the ­Sohae Satellite Launching Station began sometime between Feb. 16 and March 2, according to satellite imagery, meaning it started either just before or immediately after the breakdown of a summit meeting between President Trump and North Korean leader Kim Jong Un in Hanoi on Feb. 28.

The site, also known as Tongchang-ri, is billed as a space launch center. North Korea had said it was being dismantled and had promised to allow in international inspectors to verify that process, in a move widely cited as a sign of its good faith.

In Hanoi, Trump said Kim promised not to resume nuclear and missile tests. In that context, any move by North Korea to launch a rocket — and pass it off as a peaceful space-related activity — would probably be seen as provocative.

One bright spot: the site hasn’t been used for ICBM launches in the past. The BBC notes that this had been part of the Pyongyang space program, but that’s thin comfort:

“This distinction is important,” Jenny Town, managing editor of monitoring group 38 North, told the BBC.

“The North Koreans likely see the rebuilding not as an active part of their missile programme, but of their civilian space programme – a distinction they have made repeatedly in the past,” said Ms Town.

It’s a distinction without much difference, even if North Korea keeps making it. CSIS notes that it’s the same technology, and that it’s banned for North Korea under UN sanctions:

CSIS said activity is “evident” at the vertical engine test stand and the launch pad’s rail-mounted rocket transfer structure at the Sohae Satellite Launching Station — the facility from which Pyongyang launched satellites in 2012 and 2016.

The satellite launches were condemned by the international community and widely viewed as disguised ballistic missile tests.

The CSIS analysis said the Sohae facility “has been used in the past for satellite launches,” which use “ICBM (intercontinental ballistic missile) technology banned under UN Security Council resolutions.”

The US believes that Pyongyang’s space program is just a stalking horse for its offensive ICBM ambitions. Furthermore, it wouldn’t be impossible to use this facility for other purposes than satellite launches if Kim desired it. BBC analyst Laura Bicker believes that Kim wants to needle Trump to see how he reacts without seriously endangering the current status quo:

This renewed activity may be Pyongyang’s way of prodding Washington, just a little reminder to the Trump administration that it has the technology to build weapons and it will not give that up easily.

Most analysts believe it is more likely, at this stage, that Mr Kim is testing Mr Trump’s boundaries and patience, rather than getting ready to test a ballistic missile. …

The impoverished state could be slapped with even more economic sanctions. Mr Kim has sold these denuclearisation talks at home, and is cultivating his statesman-like image abroad – is he really ready to put that all at risk?

That depends on just how sincere Kim and his junta have been about denuclearization in the first place. Did Kim really sell denuclearization talks at home as on the level, or was the intent to see how much Kim could get away with? Does Kim care about being a statesman, or just about how much progress he can make on loosening sanctions enough to keep control at home?

If this turns into a missile test, Trump and the White House will have a tough time explaining what they gained from two summits and lots of friendly chats. The US undoubtedly gained some intel on the regime from the experience, but they likely did the same with us, too. It might prove a very disappointing stalemate all over again.