The DPRK's March 24 "Hwasong-17" launch may have been a Hwasong-15 after all

A few days ago, it became clear that the video footage released by the DPRK, purportedly of their record-breaking missile launch on the 24th of March, most likely was taken on the 16th of March. On that day the DPRK launched a missile from the same location, but it failed in flight. The video shows the new large ICBM that the DPRK first paraded through Pyongyang in October 2020, now known to be called the Hwasong-17. This missile is significantly larger than the Hwasong-15, which they first launched in November of 2017. It too was paraded through Pyongyang in 2020, which allowed a size comparison.

A simulation I did on Thursday morning showed that my Hwasong-15 computer model can recreate the March 24 trajectory, albeit with its payload reduced to little more than a heat shield. So, based on that I couldn't rule out that they had launched a Hwasong-15. According to a news report by Yonhap, US and South-Korean intelligence agencies have now confirmed that it indeed was a Hwasong-15 with a lighter warhead.

This is not the first time the DPRK has used deception. They've launched missiles with reduced payloads before and they've manipulated images to make their missiles seem bigger. We were primed to believe, by news reports and by DPRK propaganda, that the missile they launched on the 24th was a Hwasong-17 and the video seemed to confirm this. A lot of people swallowed this hook, line and sinker. I am no Cassandra, though. If I would have seen the launch footage on Thursday morning, before going to work, it's entirely likely I wouldn't have run my simulation either.

So, what do we know about the Hwasong-17? Not all that much. The size indicates it is about twice as heavy as the Hwasong-15 (something that I still hope to verify by measuring accelerations in the video) and its first stage has four engines. Their nozzle size matches those of the Hwasong-15, that uses two. So, it has about twice the thrust. We don't know its performance, because it failed in flight. But as a best guess, assuming that the Hwasong-17's second stage is similarly efficient as the Hwasong-15's, it can carry roughly twice the payload over the same distance. Based on an analysis of the Hwasong-15 I did in 2018 (presented at a conference in 2019, but not publicly available) this means a payload of 2000 kg (including the heat shield) to roughly 10,000 km.