Who can sincerely believe that President Trump fired FBI Director James Comey for any reason other than to thwart an investigation of serious crimes? Which crimes—and how serious—we can only guess.

The suggestion that Comey was fired to punish him for overzealously mishandling the Clinton email investigation appears laughable: Just this morning, Trump’s social media director Dan Scavino gleefully proposed to release video of Hillary Clinton’s concession call in order to hurt and humiliate her—and top Trump aide Kellyanne Conway laughed along with him.

No, this appears to be an attack on the integrity—not just of law enforcement—but of our defense against a foreign cyberattack on the processes of American democracy. The FBI was investigating the Trump campaign’s collusion with Russian espionage. Trump’s firing of Comey is an apparent attempt to shut that investigation down.