Putin has been a war criminal for years. Nobody cared until now.

Last week, President Biden described Russian President Vladimir Putin as “a war criminal” for ordering attacks on innocent civilians in Ukraine. For Syrians, Biden’s comments are welcome but about seven years too late, considering that the Russian military has been committing war crimes there (in collaboration with Bashar al-Assad’s regime) since 2015. Perhaps if the world had held Putin accountable then, he wouldn’t be committing war crimes in Ukraine now.

Biden’s response to a reporter’s shouted question last Thursday came after administration officials spent weeks dancing around the term “war criminal,” pending a...