Mr. Macron noticed a change in Mr. Putin’s demeanor when speaking to him on the phone over the course of the pandemic.

“He tended to talk in circles, rewriting history,” a close aide to Mr. Macron said.

That impression hardened when Mr. Macron traveled to Moscow two weeks ago as part of a diplomatic push to avert an invasion, according to French officials.

“Mr. Macron found that Putin was more rigid, more isolated, and had basically gone into a sort of ideological and security-minded drift,” a French official said.

The Kremlin’s strict health protocols also set the tone. Mr. Macron was told that if he wanted to shake Mr. Putin’s hand or sit next to him, he needed to arrive nearly seven hours before the meeting, the close presidential aide said. He would be required to take a PCR test, administered by a Russian doctor, without the French president’s doctor being present.

“The president decided a picture of him shaking hands with Putin was not worth all this,” the aide said.