It turns out that Russia has sown distrust in the U.S. political system—aided and abetted by the Democratic Party, and perhaps the FBI. This is an about-face from the dominant media narrative of the last year, and it requires a full investigation.

The Washington Post revealed Tuesday that the Hillary Clinton campaign and Democratic National Committee jointly paid for that infamous “dossier” full of Russian disinformation against Donald Trump. They filtered the payments through a U.S. law firm (Perkins Coie), which hired the...