And next here tonight, news about protecting americans the olympics. Authorities are on the alert after some troubling discoveries near the olympic site in sochi, russia, where in just 28 days,... See More
And next here tonight, news about protecting americans the olympics. Authorities are on the alert after some troubling discoveries near the olympic site in sochi, russia, where in just 28 days, america's elite athletes will join the other stars and walk in for the opening ceremony. But tonight, there are extraordinary plans being made to keep them safe. And abc's chief investigative correspondent brian ross has those. Reporter: With american athletes in the final stages of preparation for next month's winter games, there was growing concern today by u.S. Officials that terrorists will make good on their threats to attack the olympics in the russian city of sochi. I think all the ingredients are there, quite honestly. Reporter: The latest incident came today, a few hours' drive from sochi, in the city of stavropol, where police discovered four vehicles containing dead bodies, two of them, booby-trapped with powerful bombs. An apparent tactic to first lure and then kill police. In the last two months, dozens of civilians have been killed in attacks on a train station, and buses. Sochi, just 250 miles from the border of islamic terror hotbed chechnya, would be a target-rich environment for similar style attacks. Especially, say security experts, the brand-new train stations and trains here that will take athletes and spectators to the ski hills. I think these new train stations we have around sochi will be soft targets. Reporter: U.S. Officials say there will be small teams of u.S. American officials around the facility itself. And the u.S. Ski and snowboard teams have an aircraft on standby in the wake of an attack. None of this preparation can be viewed as overkill. Reporter: U.S. Olympic officials said today, they were satisfied with security but still very concerned. Everybody is very heightened on the sensitivities and what's going on. Reporter: Russia says there will be some 40,000 security personnel assigned to make sure sochi is safe. But even so, some u.S. Officials told abc news today, they are beginning to lose confidence in the ability of the russians to keep ahead of the threat that could well include targets outside of sochi, such as more train stations or airports, diane. And so soon. Thank you so much.
This transcript has been automatically generated and may not be 100% accurate.