The list of outrages committed by the government of Russian President Vladimir Putin is long and growing. The most recent is the alleged poison attack on opposition leader Alexei Navalny, who fell ill while on a plane in Russia last month. Navalny was evacuated to Germany for treatment, where tests revealed that he had been poisoned with a nerve agent. The Russian government denies the charge but evidence and logic support the accusation. Now, the world must do more than serve up pro forma verbal condemnations of this barbarism; diplomacy as usual will only encourage more such actions.

Navalny is the highest-profile opposition leader in Russia. For over a decade, he has denounced the government and ruling parties for systematic corruption in a campaign has taken root across the country. He has been jailed 13 times, and given a six-year prison sentence for embezzlement. Navalny insists those charges were a pretext to silence him: The conviction bans him from running against Putin in elections.

Apparently, preventing him from running was not enough. Instead, Navalny had to be silenced. On a flight from Siberia to Moscow, Navalny fell violently ill, forcing the plane to divert to the city of Omsk. He was admitted to a hospital there. Russian officials refused to allow him to be evacuated to Germany for treatment despite the urgings of his wife and supporters. Three days later, that decision was reversed and he was allowed to go to Berlin.