With the threat of terrorism already a major concern at the Winter Olympics in Sochi, U.S. officials are now warning that toothpaste tubes could be used to smuggle explosives onto Russia-bound airliners.

#SochiProblems: Journalists Report Horror Stories From Unfinished Hotels

Here's more on the threat from FoxNews.com:

The threat was passed on to airlines that have direct flights to Russia, including some that originate in the United States, according to a law enforcement official speaking Wednesday on condition of anonymity because he was not authorized to discuss details of the warning, which came hours before competition began at the Winter Olympics in the Black Sea resort town of Sochi, Russia. 

The official said the airlines were warned that explosive devices could be assembled in flight or upon arrival at the Olympics.

The department said in a statement that the U.S. "isn't aware of a specific threat to the homeland at this time." It said the department "regularly shares information with domestic and international partners, including those associated with international events such as the Sochi Olympics."

Delta Airlines is the only U.S. carrier with a direct flight from the United States to Moscow. Russian airlines Aeroflot and Transaero both operate several nonstop flights from the U.S.

United Airlines, the official airline of the U.S. Olympic team, does not have scheduled service to Russia but is operating some charter flights to Sochi.

The new warning comes as journalists tweet horror stories from unfinished Sochi hotels, raising further concerns about Russia's readiness for the massive event.

Elisabeth Hasselbeck sat down with former FBI special agent Mike Gilliam to get his take on the suspected toothpaste threat. Gilliam had a sobering assessment, saying he believes there's a 98% chance of at least an attempted attack taking place on something related to the Games.

"The only reason I back it off from 100 percent is that they have the motivation and in a lot of cases they have the tools and techniques to do it, but do they have the access to actually carry these out?" he said.

On the toothpaste threat, Gilliam said with such a small amount of explosives it is "highly unlikely" that such a device could bring down an airliner. He said it would have to be placed at the exact right location on the plane.

Gilliam said he is more concerned about a lack of screening for airline workers, especially outside the U.S. He characterized the chance of getting a device like this past U.S. airport security as "extremely low."

Watch his full analysis above.