WASHINGTON — The U.S. Homeland Security Department is warning airlines flying to Russia that terrorists may try to smuggle explosives on board hidden in toothpaste tubes.

The threat is to airlines that have direct flights to Russia, including some that originate in the United States, says a law enforcement official speaking on condition of anonymity because he was not authorized to discuss details of the warning.

The department said in a statement that the U.S. "isn't aware of a specific threat to the homeland at this time."

The statement notes the department — quote — "regularly shares information with domestic and international partners, including those associated with international events such as the Sochi Olympics."

The warning comes on the eve of the Winter Olympics.