Less than a fortnight after the former Russian spy Sergei Skripal was poisoned in England, another Kremlin critic has been attacked on British soil, but in this case killed.
Nikolay Glushkov was a Russian businessman who had been living in southwest London.
His apparent murder is not only shocking in its own right, it again makes it seem that his associate, Boris Berezovsky, was murdered in 2013.
This state of affairs, of repeated Russian murder bids in the United Kingdom, is both an international act of criminal aggression, and a profound political challenge.
The UK’s options are — to a depressing extent — limited. Theresa May has already expelled diplomats. Some critics want London to be an unfriendly place for wealthy Russians, which would be a major reversal of policy in which the UK capital is promoted as a safe space for rich businesses and individuals, where the rule of law prevails.
Europe is deeply reliant on Russian gas for energy, which further limits options (and raises questions as to why Britain and Germany, unlike France, have been so reticent about developing nuclear power).
At least France, Germany and America have expressed their support for the UK at this time.
Now the government will await further detail on this Glushkov murder, which if it is as it seems will result in London having to further up the pressure on Moscow.