“Putin is just trying to tie this investigation thing up,” said James Lewis, a cybersecurity expert at the Center for Strategic and International Studies.

Mr. Lewis said the Russian president “wants to assert himself as peer.” He noted that Mr. Putin again raised the proposal of a joint cybersecurity working group — an idea that Mr. Trump initially and enthusiastically supported until his staff explained the dangers of potentially undercutting American cyberdefense programs.

“He must just laugh when he gets back to Moscow,” Mr. Lewis said.

Mr. Trump’s own effort at misdirection is not new.

When he first met Mr. Putin a year ago, in Hamburg, Germany, he said the Russian leader had made a persuasive case that Moscow was so skilled at cyberattacks it could not have been involved. Mr. Trump offered a version of the same explanation on Monday, saying Mr. Putin had been enormously persuasive in his denials.

That shocked many of his current and former aides, who say the president has been briefed repeatedly — starting at Trump Tower in Manhattan in January 2017 — on the basis for the conclusion that Mr. Putin himself ordered the attack. The aides said Mr. Trump understands that American, British and Dutch intelligence all intercepted Russian messages and Democratic National Committee documents.

The American president has also been told that the F.B.I. has received a full “forensic copy” of the committee’s server. That is a fairly standard practice and, as the committee noted Monday in a statement, is “the best thing to use in an investigation so that your exploration of the server does not change the evidence.”