“By definition, intelligence means looking at pieces of a puzzle,” said Glenn S. Gerstell, who retired this year as the general counsel of the National Security Agency, before the Russian bounty issue was front and center. “It’s not unusual to have inconsistencies. And the President’s Daily Brief, not infrequently, would say that there is no unanimity in the intelligence community, and would explain the dissenting views or the lack of corroboration.”

That absence of clarity has not slowed Mr. Trump when it comes to placing new sanctions on China and Iran, who pose very different kinds of challenges to American power.

Yet the president made no apparent effort to sort through evidence on Russia, even before his most recent call with President Vladimir V. Putin, when he invited the Russian leader to a Group of 7 meeting planned for September in Washington. Russia has been banned from the group since the Crimea invasion, and Mr. Trump was essentially restoring it to the G8 over the objection of many of America’s closest allies.

The White House will not say whether he would have acted differently had he been aware of the Russian bounty for American lives.