According to a new intelligence, airlines should be on the lookout for explosives hidden in shoes on flights from overseas to the United States.
Intelligence collected by the United States and other countries has indicated terror groups have been working on new shoe-bomb designs.
"This threat is not specific or credible enough to require a specific response. Department of Homeland Security often issues these alerts out of an abundance of caution, but this does not necessarily rise to the level of facilitating a response," the intelligence official said.
The officials stressed there is no specific threat or known plot.