The population's reluctance to cooperate with police could also make identifying threats more difficult, he said.
"People don't trust security agencies," Shvedov said. "They are afraid of contacting them, because they understand they could be turned into suspects instead of being praised for their vigilance."
In 2004, terrorists rigged a new stadium in Chechnya's provincial capital of Grozny with explosives during its construction, killing the Moscow-backed regional president, the father of the province's current leader, Ramzan Kadyrov. Most analysts agree, however, that tight controls would likely have prevented such a threat in Sochi.