A Chinese company sold North Korea mobile missile launchers, in violation of UN sanctions, say Japanese government sources.
The vehicles first drew suspicion in April, after they were displayed prominently during a flamboyant military parade in Pyongyang.
Authorities searching ships docked in Japan found documents that described unloading the vehicles in North Korea, according to multiple anonymous government sources quoted in Japan's Asahi newspaper. Experts say the vehicles in the parade match the design of those known to be produced by the Chinese company linked to the sale.
The news is worrying for several reasons. First: this equipment may help North Korea conceal its weapons programme. If long-range missiles can be transported around the country, they are harder to locate and destroy. Second: it's evidence China is not being an "honest broker" in talks aimed at persuading the pariah state to give up its nuclear ambitions.
What happens now? Proving a violation of UN sanctions will be tricky. The Chinese authorities claim they were unaware the vehicles would be used for military purposes, and thought they would instead be used to transport lumber. Whether anyone believes that is beside the point: what matters is whether these revelations deter China from selling North Korea more military hardware going forward.
Learn more: The real story here is Japan's growing assertiveness towards its tricky neighbours. Simon Tisdall, writing in the Guardian, offers some excellent insight on why this is happening.