How much easier does it become for a state to deploy chemical weapons when its government has already tolerated and sought to hide their use by others? I would draw a connection between Putin’s indulgence of Assad’s atrocities in Syria and the Russian state’s evident willingness to employ a chemical weapon on British soil.

There is a reason for choosing Novichok. In its blatant Russian-ness, the nerve agent sends a signal to all who may be thinking of dissent in the intensifying repression of Putin’s Russia. The message is clear: We will find you, we will catch you, we will kill you — and though we will deny it with lip-curling scorn, the world will know beyond doubt that Russia did it.

As a permanent member of the U.N. Security Council, Russia has a special obligation to uphold the rules of good international conduct. When it does the opposite and tramples upon these rules, the Kremlin threatens the very architecture of global security.