Senior Obama officials debating the U.S. response say they believe the Russian president is making a costly mistake that he will regret, committing his country’s military and prestige to an unwinnable fight sure to inflame Islamic extremism inside Russia.

But Putin hardly seemed chastened, and even appeared to accuse the U.S. of lying about the Russian airstrikes. Speaking in Moscow, Putin claimed that reports about civilian casualties from the strikes had “emerged even before our planes got on in the air.”

“We are prepared for such information attacks,” Putin said.

U.S. officials continued to say that Russia was striking areas far from the strongholds of the Islamic State, also known as ISIS. Nor did they dispute reports — which Senate Armed Services Chairman John McCain (R-Ariz.) said he had independently confirmed — that Russia had bombed some moderate rebel fighters who have been covertly supplied by the CIA. Putin denied that Russian any strikes had hit CIA-backed rebels.