The U.S. government has warned airlines about a potential shoe bomb threat on international flights to the United States.
The Department of Homeland Security said Wednesday it issued a warning based on "very recent intelligence" considered credible that assailants would try to attack passenger jets using explosives hidden in shoes.
It is the second time in three months that the government has issued a warning about possible attempts to smuggle explosives on a commercial jetliner.
U.S. intelligence sources said the DHS released a notice to airlines reiterating that liquids, shoes and certain cosmetics were of concern, all of which are covered under existing Transportation Security Administration security policies.
It is not clear if the latest warning, first reported Wednesday by NBC News, is related to earlier threats to Russia-bound flights.
Earlier this month, the DHS warned airlines with flights to Russia to be on the lookout for explosive devices possibly hidden inside toothpaste tubes.