Russian President Vladimir Putin has shrugged off criticism over his annexation of Crimea, sanctions over his meddling in Ukraine, and attacks over Russian interference in the U.S. elections. It will be much harder to shrug off international outrage over the use of a chemical agent in a NATO ally.

No matter what they say officially, neither U.S. nor European officials are particularly bothered about Ukraine, a poor, corrupt country on the Soviet periphery that the West isn’t bound by any treaties to defend. So sanctions on Russia for invading Ukraine and fomenting unrest there have been weak. It also has been hard for the U.S. to get European cooperation for any retaliatory measures tied to the election meddling issue. The use of chemical weapons is a different story. The Chemical Weapons Convention, which bans them, has 192 signatory states, one fewer than the United Nations Charter; it’s one of the most universally approved international documents in history. Breaking it can entail far more serious sanctions than those Russia has faced for its earlier attempts to assert itself globally.

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