However, additional checks not only add to the hassles for air travelers but risk creating another line of people vulnerable to terror attack.
"Any movement of the security 'comb' to the public entrance of a terminal building would cause congestion, inconvenience and flight delays, while the inevitable resulting [lines] would themselves present an attractive target," said Ben Vogel, the editor of IHS Jane's Airport Review.
"We call it transferred risk, where you are simply moving the vulnerable point rather than eliminating it," said Simon Bennett, director of the Civil Safety and Security Unit at England's University of Leicester.
It is also costly. "Politicians cannot say it, but security experts can — it would be prohibitively expensive to have extra manned security checkpoints at entrances to airport terminals," Bennett said. "The cost would not be worth the benefits."
In Israel, where aviation security is regarded as the most effective in the world, passengers are not automatically screened before approaching airport buildings. Instead, they are subject to profiling in which they pass through checkpoints manned by military or security officials trained to spot and detain anyone most likely to pose a risk.
However, profiling comes at a huge risk to civil liberties — with citizens picked on because of their race or religion.