The United States is advising airlines with direct flights serving Russia to be aware of the possibility that explosive materials could be concealed in toothpaste or cosmetic tubes, the chairman of the House Homeland Security Committee said Wednesday night.
Rep. Michael McCaul said the Department of Homeland Security issued a bulletin to airlines flying into Russia warning of the potential threat.
The bulletin, the Texas Republican said, indicated that officials believed the explosives might be used during flights or smuggled into the city of Sochi, where competition at the Winter Olympics begins Thursday. The opening ceremony is Friday.
A U.S. law enforcement official told CNN that the cause for the Homeland Security alert was specific to the imminent start of the games.
According to the source, authorities have increasing confidence about the safety of Sochi and the Olympic venues. Still, U.S. intelligence is picking up increasing chatter that causes worry about targets outside the Sochi area, including regional transportation links.
The biggest ongoing worry outside this new concern - as expected - is groups based in southern Russia's Caucasus region, in particular the restive Dagestan republic.
However, U.S. officials also are worried that al Qaeda-linked groups from elsewhere could take advantage of the attention being focused on Russian militant groups.
The concern about the use of toothpaste tubes is mostly focused on flights from Europe and neighboring Asian countries - in part because the United States has less intelligence-sharing with those nations.
A separate U.S. official with knowledge of the current situation, who would not speak on the record because of the sensitivity of the situation, said the U.S. intelligence community is still assessing the credibility and scope of the threat.
The official said the Russians brought some information to the United States. Two senior administration officials told CNN that U.S. authorities had intelligence that they shared with the Russians.
Assessing the credibility includes looking at the latest intelligence about the location and capabilities of known terrorist bomb makers and which groups may have the ability to build a bomb in a container such as a toothpaste tube. Such a device would likely require hard-to-detect explosives and little or no metal content in other critical parts, such as the detonator.