Matthew Olsen, director of the National Counterterrorism Center, told the Senate Intelligence Committee that there is extensive security at the sports venues in Sochi.
But, he added, "The greater threat is to softer targets in the greater Sochi area, and in the outskirts, beyond Sochi, where there is a substantial potential for a terrorist attack."
FBI Director James Comey told the panel that U.S. cooperation with the Russian Security Service has improved, and officials from the two agencies have discussed the Sochi threat.
In a separate development, Defense Secretary Chuck Hagel spoke Wednesday with Russian Defense Minister Sergei Shoigu to discuss Olympic security. Hagel pledged U.S. assistance, if requested. Pentagon press secretary Rear Adm. John Kirby said Hagel made no specific offer of aid, and Shoigu made no particular requests.
But Kirby said the two leaders agreed that their military officers would continue some type of regular contact through the Games in order to keep communication lines open in case assistance was needed.
Russia is mounting a massive security operation for the Olympics, deploying more than 50,000 police and soldiers amid threats from Muslim insurgents from the nearby Caucasus region.
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