According to several former Obama administration officials and former Italian officials familiar with the conversation, Mr. Obama berated the brash former mayor of Florence, saying this was high-stakes global politics, not a City Council meeting in Florence.
“He took his head off,” said one former Obama administration official with knowledge of the call.
After that, Mr. Renzi didn’t waver, despite facing mounting pressure over the sanctions. He ultimately earned the respect of Mr. Obama for upholding liberal democratic values, but he also apparently drew the anger of Mr. Putin.
In his book, Mr. Renzi suggests that the RT episode and the spreading of disinformation on social media raise “questions that a mature democracy needs to ask itself to avoid underestimating a crucial topic in our time: How do we regulate social-media connected phenomena?”
Those questions are now front and center as European Parliament elections approach in May and another American presidential election looms next year.
Just three years ago, in more innocent (or naïve) times, Mr. Renzi and François Hollande, then president of France, had raised the issue of foreign interference during an April 25, 2016, meeting in Hannover, Germany, with Mr. Obama, Chancellor Angela Merkel of Germany and Prime Minister David Cameron of Britain.
The discussion quickly turned to Russia and the strong suspicion of a connection between Mr. Putin and the National Front party in France of Marine Le Pen, Mr. Renzi writes, confirming previous reports.
Ms. Merkel was, he writes, “the most skeptical about the importance of ‘fake news.’ ”