Although the Russians are relying on a show of force at the Games, deploying 40,000 heavily armed police and other security officials to the area, the security risks are regarded as unusually high compared with past Olympics. The main threat emanates from Islamic radicals who are based in the nearby Caucasus and who have vowed to launch attacks during the event. …

Former FBI agent Jim Treacy, who also worked in Moscow as a legal attache, said the Russians would be “equally concerned as our folks being involved in intelligence-gathering while doing security and counterterrorism.”

Rubincam said that by September 2011, he had started trying to work with the Russians in planning for Sochi. The discussions were complicated by larger diplomatic strains in the relationship that only deepened after Vladi­mir Putin returned to the presidency in 2012.

“When I got there, the cooperation on terrorism had fallen to zero,” Rubincam said. The limits of the relationship were highlighted by the Boston Marathon bombing, after which U.S. and Russian officials blamed each other for not following through on leads that might have identified two ethnic Chechen brothers before they were implicated in carrying out the attack.