No matter how low your expectations for the summit between Donald Trump and Vladimir Putin on Monday, it was hard not to be staggered by the American president’s slavish and toadying performance.

On Friday, the Justice Department indicted 12 members of Russia’s military intelligence service for a criminal conspiracy to interfere with the 2016 election and hurt Hillary Clinton’s campaign. The same day, Trump’s director of national intelligence, Dan Coats, gave a speech about America’s vulnerability to cyberattacks, particularly from Russia. “I’m here to say, the warning lights are blinking red again,” he said, comparing the threat to the one that preceded Sept. 11.

But standing beside Putin in Helsinki on Monday, Trump sided with the Russian president against American intelligence agencies while spewing lies and conspiracy theories. “He just said it’s not Russia,” he said of Putin’s denials. “I will say this. I don’t see any reason why it would be.” Continuing in a free-associative fugue, he asked, “What happened to the servers of the Pakistani gentleman that worked on the D.N.C.?” referring to a debunked right-wing claim about a former Democratic I.T. staffer. “What happened to Hillary Clinton’s emails? Thirty-three thousand emails gone, just gone. I think in Russia they wouldn’t be gone so easily.”

Perhaps the most sinister part of the news conference was Trump’s seeming openness to a deal in which F.B.I. investigators could question people in Russia in exchange for letting Russians question Putin critics in America. Putin referred specifically to associates of his arch-nemesis Bill Browder, a businessman (and British citizen) who has succeeded in getting seven countries, including the United States, to pass laws punishing Russian oligarchs suspected of corruption. (The Russians who met with members of the Trump campaign at Trump Tower in June 2016 wanted to discuss this law, the Magnitsky Act.)