If enhanced security measures are justified, then they are based upon what...???
Reasonable suspicion.
Customs officials have been screening potential suspects for decades -- long before terrorism became a household word. The professionals develop a sixth sense of identifying when someone warrants special attention. A person's demeanor and nonverbal cues are far better indicators than their race or religion.
Bingo...!!!
Look at the illustration below...
Whenever we see certain visual cues, we immediately form associations of those cues to certain behaviors, or at least of certain behaviors. For the 'soldier', even if we do not see a weapon, we associate his wearing of the uniform to weapons, to war, to destruction, and ultimately to death. For the 'civilian', when we see the camera, we associate this instrument to tourism, to travel, to decadence, to food, to businesses, and ultimately to peace and long life.
These visual cues are so important that they are codified into the conducts of war...
Geneva Convention relative to the Treatment of Prisoners of War, 75 U.N.T.S. 135, entered into force Oct. 21, 1950.
(a) That of being commanded by a person responsible for his subordinates;
(b) That of having a fixed distinctive sign recognizable at a distance;
(c) That of carrying arms openly;
(d) That of conducting their operations in accordance with the laws and customs of war.
What the Islamic jihadists have done was to turn ordinary garbs that are associated with muslim civilians into visual cues of war. A religious war. So for those of us who, not only are used to but actually instilled from birth, to associate certain restricted visual cues to war, to encounter something that goes contrary to what we demand and expect, what do you think is going to happen? Like it or not, we will do
EXACTLY what the Islamic jihadists have done: To associate a civilian, which is burqa-ed woman, a holy text, and a loud praise to a deity, with violence, war, and death.