Assad has committed many terrible crimes against his people, but if these latest reports are confirmed, he will have entered into the pantheon of the modern era’s worst war criminals, just as Saddam did in 1988. Back then, Saddam was considered an ally by the U.S. (he was in the midst of a war with Iran). So, to the everlasting shame of President Ronald Reagan, the U.S. did nothing to stop his genocide.

Here is a chance to make amends, not to the Iraqi victims of chemical weapons, but to the notion, shared by all non- sociopathic people, that there are things that human beings simply don’t do to each other. Obama has been rightly criticized for drawing a line in the sand on chemical weapons. His statements communicated to Assad that he was free to massacre his people using conventional means without fear of undue American molestation. If Assad has indeed crossed this line, he has invited armed intervention. And if that intervention doesn’t come, the consequences — moral and political — could be long- lasting…

At which point Obama has some choices to make. He could use force to begin destroying or safeguarding Syria’s chemical weapons stockpiles. This is dangerous, of course, and could even involve the insertion of U.S. special operations forces trained in such work. Obama’s other options include establishing no-fly zones and openly arming Syria’s rebels, steps that could lead to the quicker collapse of the regime. No-fly zones are expensive and hazardous to maintain, but they would go a long way toward degrading Assad’s power. Arming the rebels is similarly fraught, because many of them are the sorts of people who seem likely to one day turn these weapons back on the U.S. or its friends.