jim, what are you hearing from your sources? >> reporter: wolf, two key points here. one, that this probe into these phone calls is continuing. it is still under way. second, that it relates not just to the fact that these phone calls took place, but also the content of those phone calls. what was said on the phone. again, that investigation continuing. tonight, u.s. counter intelligence investigators are scrutinizing phone calls between president trump's national security adviser, general michael flynn, and the russian ambassador to the u.s. law enforcement and intelligence officials tell cnn. some of the calls in question were made on december 29th. the very same day the obama administration announced retaliation for russia's unprecedented cyberattack of the 2016 presidential election. retaliation, which included further sanctions on russia and the expulsion of some 35 russian diplomats. the content of those calls, captured through routine