Official Moscow can try to insist that its last chemical weapons were destroyed last year. It can also try a tactic it developed in Syria, claiming the use of the chemical was a false flag operation (perhaps blaming Ukraine, as some commentators on Russian state TV have already said). Both these lines of defense, however, are likely to grow less credible as the British investigation progresses, especially if it's established with reasonable certainty that the nerve agent could only have been deployed by someone linked to the Russian government. No country will condone the use of chemical weapons, whatever the economic consequences of a harsh sanction regime.
Putin's Kremlin will probably ignore the early warnings and keep up its brinkmanship. It may find this a mistake soon, as countries are faced with evidence of a Russian chemical weapon deployment on foreign soil.
Leonid Bershidsky is a Bloomberg View columnist. He was the founding editor of the Russian business daily Vedomosti and founded the opinion website Slon.ru.
This column was provided by Bloomberg News.