THE ENDURING image of the U.S.-Russia summit in Helsinki on Monday will be that of President Trump standing next to Vladi­mir Putin and suggesting he found Mr. Putin’s “powerful” denial at least as persuasive as the U.S. intelligence community’s unanimous finding that Russia intervened in the 2016 election. Coupled with another groundless attack on the FBI and an apparent endorsement of a patently disingenuous offer by Mr. Putin to collaborate with the investigation of special counsel Robert S. Mueller III, Mr. Trump appeared to align himself with the Kremlin against American law enforcement before the Russian ruler and a global audience.

Mr. Trump had said he would raise the issue of Russia’s interference in the election with Mr. Putin, but the result was a series of statements that could have been scripted by Moscow. Mr. Trump said that, while Daniel Coats, the United States’ director of national intelligence, had told him Russia was responsible for hacking into the server of the Democratic National Committee, “I don’t see any reason why it would be.” He referred to various discredited conspiracy theories about the hack while lambasting the FBI. When offered an open-ended opportunity to cite any behavior by Russia that had contributed to poor relations, the president sidestepped, saying, “I hold both countries responsible.” As Mr. Trump apparently sees it, Russia’s invasions of Ukraine and Georgia, war crimes in Syria, poison attack in Britain and the shooting down of a Malaysian civilian airliner over Ukraine are morally equivalent to the policies pursued by previous U.S. administrations.

It’s not yet known what Mr. Trump and Mr. Putin discussed in their private meeting, or whether they reached any tangible agreements. Both leaders suggested there had been accord on securing Israel’s border with Syria and on providing humanitarian aid to Syrian refugees, though they offered no details. Even if he obtained nothing concrete from Mr. Trump, Mr. Putin scored a symbolic triumph by appearing to stand as an equal with the U.S. president in a relationship with “special responsibility for maintaining international security,” as he put it.

While Mr. Trump’s insistence on granting Mr. Putin that status was misguided, it paled beside his betrayal of the FBI and his own senior intelligence officials. Incredibly, Mr. Trump appeared to endorse a cynical suggestion by Mr. Putin that Mr. Mueller’s investigators be granted interviews with a dozen Russian intelligence officers indicted in the DNC hack in exchange for Russian access to associates of William Browder, a financier whose exposure of high-level corruption and human rights crimes in Moscow led to the adoption by Congress of the Magnitsky Act, which imposed sanctions on those responsible. Mr. Putin’s citation of bogus Russian charges against Mr. Browder was matched by Mr. Trump’s garbled reference to “the Pakistani gentleman” who was falsely alleged by right-wing conspiracy theorists to be behind the leak of DNC emails.

In Helsinki, Mr. Trump again insisted “there was no collusion” with Russia. Yet in refusing to acknowledge the plain facts about Russia’s behavior, while trashing his own country’s justice system, Mr. Trump in fact was openly colluding with the criminal leader of a hostile power.