SOCHI, Russia (AP) -- While Sochi's Olympic venues are now among the most tightly guarded facilities in the world, the rest of this sprawling Black Sea resort looks more vulnerable.
With about 100,000 police, security agents and army troops flooding Sochi, Russia has pledged to ensure "the safest Olympics in history." But terror fears fueled by recent suicide bombings have left athletes, spectators and officials worldwide jittery about potential threats.
Security experts warn that Islamic militants in the Caucasus, who have threatened to derail the Winter Games that run from Feb. 7-23, could achieve their goal by choosing soft targets away from the Olympic sites or even outside Sochi. Some have raised the possibility that jihadists could have infiltrated Sochi long before security was tightened and have noted the vulnerability of the city's transport systems.
"The most daunting threat is suicide bombers," Grigory Shvedov, chief editor of the Caucasian Knot, an online news portal focusing on the Caucasus, told The Associated Press.
He said 124 suicide attackers have struck Russia over the past 13 years.
Air defense missiles, drones, high-speed patrol boats and sophisticated sonars capable of spotting submarines -- the array of high-tech gear deployed makes Sochi look like it's preparing for an enemy invasion from both air and sea. Observers question, however, to what extent the Russian security agencies are prepared to respond to the most likely threat -- suicide bombers with primitive explosives strapped to their bodies.
The back-to-back December suicide bombings of a railway station and a bus in Volgograd, about 640 kilometers (400 miles) east of Sochi, killed 34 people and demonstrated the militants' ability to strike with shocking ease. A jihadist group in Dagestan, the epicenter of the Islamic rebellion against Russia that has engulfed the Caucasus, claimed responsibility for the Volgograd bombings and has threatened to strike Sochi. Dagestan is only a few hundred miles (kilometers) from Sochi.
Police in Sochi issued leaflets recently warning about three potential suicide bombers, one of whom, a 22-year-old widow of an Islamic militant, was said to be at large in the city. The notices have raised questions about efficiency of the rigid security measures in Sochi, which have involved the expulsion of thousands of migrant workers and blanket police checks of city residents.
Alexander Popkov, a Sochi-based lawyer who has defended local activists, said door-to-door searches in Sochi were conducted in two waves. During the first in September and October, police and the Federal Migration Service conducted extensive checks, working with 60 teams around the clock from district to district to try to reach every home.
Despite this large-scale effort, the searches in Sochi were "superficial and could only uncover some outlaws or illegal migrants," Popkov said. "I don't think they would have uncovered a terrorist cell."
Russian police -- who did not have ad-hoc powers to search people's homes -- would sometimes turn back when an intractable resident refused to open the door.
"I know my rights, so I knew how to say no. When they went to my house, I immediately refused," Popkov said.
Those who allowed policemen in were asked to fill in elaborate forms "as if you were applying for a loan," he said.
The second wave of checks in November and December mostly targeted activists, who were forced to sign letters pledging not to commit misdemeanors during the games. Some activists said policemen told them they had a long list of people to pay special attention to -- including drug addicts, alcoholics, ex-convicts and activists -- but they had no idea who fit in which category.
Popkov said one woman was summoned to go to the police station but "later they told her: I see you are not an extremist, you don't have to come."
Andrei Soldatov, an independent Moscow-based security analyst, described the police raids as a throwback to Soviet times.
"They follow the Soviet methods while working to ensure security, trying to establish control over activists and dissenters," he said. "Control is a key word for them, but it's not synonymous with security."
Soldatov said jihadists fighting to carve out an independent Islamic state in the Caucasus could have placed sleeper agents in Sochi years ago.
"The probability of that is quite high, they had plenty of time to prepare," he said.
Shvedov, the Caucasian Knot editor, agrees.
"If they wanted to get explosives in Sochi, they could have done it well before the attacks in Volgograd, when massive construction work was underway and there was little control over people who flowed into the city," Shvedov said.