Some U.S. troops carry hand-held devices to capture faces, eyes and fingerprints of "known and suspected insurgents, " according to Lt.

WSJ: Police Adopting iPhone-Based Facial-Recognition Device by BI2, Raising Civil-Rights Questions

On one hand, they carry high-priced items that they want to protect.

FORBES: Why Do People Steal Meat From Grocery Stores?

As well as having to undergo more stringent checks, passengers are also being limited to one piece of carry-on hand luggage.

BBC: Airport security measures

Travellers should also consider printing out boarding passes ahead of time to speed up the check-in process, and should remember the rules about packing liquids and electronics in carry-on and hand luggage.

BBC: Navigating the London 2012 exodus

It therefore seems problematic to me when such lively, well-informed and yet largely unresolved debates get reduced to six key messages, messages that on the one hand carry the aura of urgency, precision and scientific authority - "there is no excuse for inaction" - and yet at the same time remain so imprecise as to dictate or resolve nothing in political terms.

BBC: What message, and whose, from Copenhagen?

On the other hand, searching for the knives on passengers or in their carry-on bags is time consuming, Pistole said.

NPR: TSA Stands By Plan To Allow Small Knives On Planes

Since the message was not posted on the radical Islamist Web sites that usually carry statements from al Qaeda, it is believed that this latest message was hand-delivered to the TV network, based in Doha, Qatar.

CNN: Purported bin Laden tape slams U.S. role in Pakistan