Deputy Attorney General Rod J. Rosenstein speaks during a news conference at the Justice Department on July 13 in Washington. (Evan Vucci/AP)

JUST THREE days before President Trump’s planned meeting with Russian President Vladimir Putin, the Justice Department reminded everyone why Mr. Putin is not merely a competitor or potential friend, as Mr. Trump has termed him recently, but an implacably hostile foreign adversary.

Deputy Attorney General Rod J. Rosenstein announced the indictment of 12 Russian military officers allegedly involved in hacking the 2016 U.S. presidential election. The document detailed how the Russian government “conducted large-scale cyber operations to interfere” with the election, “staged releases of documents stolen through computer intrusions,” and used cryptocurrency to assemble a network of computers to mask their operations. They allegedly targeted more than 300 people involved in the 2016 Democratic campaign effort, including Clinton campaign chairman John Podesta, monitoring the computers and stealing the emails of dozens, before coordinating with others to publish them at strategically crucial moments.

There are many questions the indictment leaves unanswered, including how many Americans were in contact with the Russian hackers. The indictment mentions communications with a U.S. congressional candidate and someone in regular contact with senior Trump campaign officials. It also notes that the Russians stepped up their hacking just as Mr. Trump was calling on them to obtain and release Hillary Clinton’s emails.

The indictment says enough that Mr. Trump cannot ignore it as he prepares to meet with Mr. Putin. In the runup to the summit, Mr. Trump has said he would raise the issue of Russian election meddling. Yet he left little hope that he would do so with the force the matter deserves. “All I can do is say, ‘Did you?’ and ‘Don’t do it again,’ ” Mr. Trump said on Thursday. That is far from all he could say. He could point to the indictments and say, “We know you did this, here are the sanctions you will suffer for it, and here are the additional sanctions we will impose if you do it again.”

Yet Mr. Trump, who was briefed on the indictment earlier this week, seems not to have taken its implications seriously. This week he repeatedly called the Justice Department’s Russia investigation, which generated the indictment, a “witch hunt.” In fact, the indictment is yet more proof that the probe continues to uncover serious misdeeds and pin criminal blame on those responsible. On top of these and a previous batch of indictments, special counsel Robert S. Mueller III has already secured five guilty pleas.

House Republicans spent much of Thursday attempting once again to aid Mr. Trump in tarring the FBI and, by extension, Mr. Mueller’s investigation. But the facts speak louder than all the hot air in their show hearings. The country — and all its leaders — must keep top of mind that the Russian government meddled in the nation’s democratic process and plans to do so again. The Russians should be punished and deterred. Ignoring or minimizing these overriding points is an abdication of responsibility.