This is what you might call a non-specific warning. In other words, there's no specific target/airline or time frame. But, Department of Homeland Security officials are talking, specifically, about shoe bombs. They're also saying, on a scale of 1 to 10, this alert is a level 5 or moderate threat.
But, security expert Aaron Cohen says, regardless of the level, a "shoe-bomb" alert is significant. In this case, DHS has warned airlines to pay extra attention to shoes on feet and shoes in bags especially from people coming on International flights into U-S airports. Cohen says shoe bomb explosives are significant because they are small. "We are talking about something the size of a half of a roll of quarters," he says.
And, they can be undetectable. Says Cohen, "It's something that could easily get by security because it's something that everybody wears (Hal: there's no buzzers that go off when a shoe bomb comes thru?) there wouldn't be if it were prepared correctly."
Cohen says this will mean more scrutiny at screening stations. Not just for shoes, but swab testing. "They're going be swabbing for plastique-like explosives like semtex or residue on shoes or someone's hands."
Cohen takes this latest warning as a sign of getting better at hearing chatter and acting on possible threats. Says the security expert from IMS Security in Beverly Hills, "I think we're getting better at terrorism, or counter terrorism, and I think when that information gets picked up in the field it gets up by a myriad of agencies that begin to decipher it."
From there, if it does seem credible bulletins are issued like this latest one.