The following seems to have been written completely seriously:
Don’t forget that Mr. Mueller has already secured guilty pleas showing ties between Mr. Trump’s campaign and the Russian government, including from one foreign-policy adviser to the campaign who lied to authorities about his communications with a professor who offered damaging information on Mrs. Clinton — a professor he knew was linked to Russian officials.
The dash is needed to avoid a third “who” in this ridiculous sentence.
Russian officials attacked American democracy in 2016, and the intelligence community has warned us that they’re coming back for more. But Mr. Trump seems incapable of perceiving the threat.
And he’s not alone.