In fact, there are already piles of evidence that Mr. Trump and top officials in his campaign were not only aware of the Russian hacking at the time, but were encouraging it. Remember the July 2016 news conference where Mr. Trump asked Russia to hack Mrs. Clinton’s emails? “Russia, if you’re listening, I hope you’re able to find the 30,000 emails that are missing,” he said. Another “joke,” his defenders claimed at the time. On or about the same day, according to the indictment, the Russians tried to hack into multiple email accounts used by Mrs. Clinton’s personal office, as well as dozens more associated with her campaign.

And then there was Donald Trump Jr.’s response to a June 2016 email offering “dirt” on Mrs. Clinton from a Russian government official. “This is obviously very high level and sensitive information but is part of Russia and its government’s support for Mr. Trump,” the message said. Donald Jr., who was one of his father’s top campaign aides, immediately replied, “If it’s what you say I love it especially later in the summer.”

Friday’s indictment included more than a few hints about the next targets of Mr. Mueller’s investigation. For example, in August 2016, a candidate for Congress requested stolen documents from Guccifer 2.0, who sent documents related to that candidate’s opponent.

On the same day, Guccifer wrote to a person “in regular contact with senior members” of the Trump campaign, apparently Roger Stone, “thank u for writing back … do u find anything interesting in the docs I posted?” A couple of days later, Guccifer wrote, “please tell me if i can help u anyhow … it would be a great pleasure to me.”

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.

Responding to this shouldn’t be difficult. 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, while Republicans in Congress spend their time fulminating not about the assault on American sovereignty, but about the private text messages of an F.B.I. agent investigating that attack.

As Deputy Attorney General Rod Rosenstein rightly said after announcing the indictment, in the face of such an assault, “it’s important for us to avoid thinking politically, as Republicans or Democrats, and instead to think patriotically as Americans.”

Good advice. If only Mr. Trump and his servile defenders in Congress would heed it.

Follow The New York Times Opinion section on Facebook and Twitter (@NYTOpinion), and sign up for the Opinion Today newsletter.