Trump’s silence is easy fuel for his critics, who have long said that he is too weak on Russian President Vladimir Putin after alleged Russian interference in the 2016 U.S. election. “Any other U.S. President would have condemned the attack immediately,” Sen. Richard J. Durbin (D-Ill.) tweeted on Wednesday.

It has also angered Russian opposition leaders who argue Putin acts with impunity. “There is a historical term for this kind of policy, and that historical term is appeasement,” Vladimir Kara-Murza, an activist and writer who has himself survived two suspected poisonings, told MSNBC over the weekend.

The muted presidential response is hardly a surprise, however. From the earliest days of his presidency, Trump has shown little desire to criticize Putin, even when his own officials pushed for sanctions and other reprimands for Moscow. Trump has shown scant sympathy for political activists anywhere in the world, let alone in Russia.