This then raises the question of how many of these missiles the North Koreans can produce. The South Korean government recently observed North Korea has sent 6,700 containers of munitions to Russia, it says that Pyongyang's weapons factories were operating at full-tilt, and Dr Lewis, who has been studying these factories through satellites, reckons they can churn out a few hundred a year.
Still reeling from their discovery, Mr Spleeters and his team are now trying to work out how this is possible, given that companies are banned from selling parts to North Korea.
Many of the computer chips that are integral to modern weapons, that guide them through the air to their intended targets, are the same chips that are used to power our phones, washing machines and cars, Mr Spleeters explained.
These are being sold all over the world in staggering numbers. Manufacturers sell to distributors in their billions, who sell them on in their millions, meaning they often have no idea where their products end up.
Even so, Mr Byrne was frustrated to learn how many components in the missile had come from the West. It proved that North Korea's procurement networks were more robust and effective than even he, who investigates these networks, had realised.
From his experience, North Koreans based overseas set up fake companies in Hong Kong or other central Asian countries to buy the items using predominantly stolen cash. They then send the products onto North Korea, usually over its border with China. If a fake company is discovered and sanctioned, another will quickly pop up in its place.
Sanctions have long been considered an imperfect tool to combat these networks, but to have any hope of working they need to be regularly updated and enforced. Both Russia and China have refused to impose new sanctions on North Korea since 2017.
By buying Pyongyang's weapons, Moscow is now violating the very sanctions it once voted for as a member of the UN Security Council. Then earlier this year it effectively disbanded a UN panel that monitored sanctions breaches, likely to avoid scrutiny.
"We are witnessing the real-time crumbling of UN sanctions against North Korea, which buys Pyongyang a lot of breathing space", Mr Byrne said.
All this has implications that reach far beyond the war in Ukraine.
"The real winners here are the North Koreans", said Mr Byrne. "They have helped the Russians in a significant way, and this has bought them a tonne of leverage".
In March, RUSI documented large amounts of oil being shipped from Russia to North Korea, while railcars filled with what are thought to be rice and flour have been spotted crossing the countries' land border. This deal, thought to be worth hundreds of millions of pounds, will boost not only Pyongyang's economy, but its military.