Matthew Olsen, director of the National Counterterrorism Center, is telling Congress Tuesday that the U.S. and Russia are tracking threats of "varying degrees" of credibility. He said potential attacks seem more likely outside the venues for the games, and instead in the area or region around Sochi.
He described intelligence sharing with Russia as "good."
FBI Director James Comey said U.S. co-operation with the Russian Security Service has improved.
Russia has mounted a massive security operation for the Olympics, deploying more than 50,000 police and soldiers amid threats from Muslim insurgents.