While US Transportation Security Administration officers relentlessly made sure that my 83-year-old, wheelchair-bound mother-in-law was not smuggling a shoe bomb onto her plane recently, was anyone thwarting an attack by a real terrorist? The answer, unfortunately, is no. Living in Israel, a country where every supermarket and cafÃ© has a guard with a metal detector, I looked in vain for real security at the four US airports I passed through last month. It was clear that the TSA is mostly engaged in providing an illusion of security, while ignoring real threats. For example, TSA guards defending boarding gates unerringly target liquids in containers holding more than one ounce, for fear larger quantities might be combined in a binary explosive device. That's what their security protocol says - even though the contents of a permitted number of small containers could be lethally combined on a plane by a not very sophisticated bomber, if they in fact contained explosive liquids. This becomes a mockery of security when TSA guards vehemently confiscate sealed bottles of mineral water under the same faulty pretext. I watched dumbfounded as one dropped my $3 half-liter bottle of water into a garbage can - and refused to let me drink it "for security reasons." While an army of TSA officers makes a good show of securing the gates, there are no guards monitoring access to the airport itself. No matter that the only shoe bomber on record was a schlemiel who couldn't even light a match to his shoe, as if his device would have worked anyway. He is in prison, but each day millions of airline passengers throughout the world must doff their shoes and pass inspection. At least there was once a real would-be shoe bomber - the persistent liquid explosive "menace" is the result of a rumor. The security measures at US airport gates are fearsome. The numerous guards in their spiffy uniforms are so tough, there is even an electric sign at Newark's Liberty Airport warning passengers against voicing jokes about security - on penalty of prosecution. But it is the TSA that is a joke. ALL THOSE BILLIONS of dollars, all that high-level training in shoe and water bottle scrutiny, is invested in guarding the wrong place. No suicide bomber in his or her right mind would try to slip an explosive device past the TSA at the sensitive entrance to the boarding gates. A terrorist doesn't have to, for the TSA guards the wrong perimeter. The boarding gate is the final hurdle for a terrorist whose particular preference is to slaughter innocents only in the air. A much easier target is the unguarded departure hall, which is freely accessible to the public at US airports. At Ben-Gurion Airport, to get as far as the boarding gate, a passenger must first pass through several concentric rings of security checks. Unlike at US airports, vehicles approaching Ben-Gurion are checked at the outermost perimeter by guards armed with automatic weapons. Passengers dropped off with their luggage are then given the once over by more subtle plainclothes guards as they enter the terminal. Before a passenger can approach the ticket counter, he or she is briefly, but carefully interviewed by another security guard. Then the luggage is X-rayed. Even the ground stewardess at the counter is trained to look for anything suspect about the passenger, including the travel documents. Then the passenger must show passport and boarding pass again before doffing shoes and being body scanned, and proceeding to yet another check at passport control. In the US, however, while the earnest gate sentries of the TSA are ensuring that grandma's shoes are not lethal, there is virtually no protection against a multiple suicide attack in a more vulnerable part of the airport. While the TSA defends only the back door, there is nothing to deter several terrorists carrying suitcase bombs from walking through the terminal's front door and detonating them in the midst of a thousand innocent travelers. The writer is a former chief copy editor of The Jerusalem Post.