Two weeks before his inauguration, Donald J. Trump was shown highly classified intelligence indicating that President Vladimir V. Putin of Russia had personally ordered complex cyberattacks to sway the 2016 American election.

The evidence included texts and emails from Russian military officers and information gleaned from a top-secret source close to Mr. Putin, who had described to the C.I.A. how the Kremlin decided to execute its campaign of hacking and disinformation.

Mr. Trump sounded grudgingly convinced, according to several people who attended the intelligence briefing. But ever since, Mr. Trump has tried to cloud the very clear findings that he received on Jan. 6, 2017, which his own intelligence leaders have unanimously endorsed.

The shifting narrative underscores the degree to which Mr. Trump regularly picks and chooses intelligence to suit his political purposes. That has never been more clear than this week.