I have my doubts about that as well. I would think that the lack of K-9 teams near departure gates is a good sign that bombings are not the concern of the TSA when it comes to airport security. Bombings are probably a concern somewhere, but the security checkpoints do not seem to do much when it comes to stopping a bomb plot.
Keep in mind that private planes are exempt from the security checks. If a terrorist wanted to blow up a commercial plane, what would stop them from chartering a private jet, bringing bombs on board, and then ramming their explosive-laden plane into an airliner mid-flight? Why even bother doing it in flight? A terrorist might just roll their chartered jet into a fully-loaded passenger plane on the runway, and blow up a plane in front of a crowd of people.
Perhaps there is some other procedure in place to ensure that no bombs can make it past the numerous ways that people and vehicles can enter an airport without going through a security checkpoint. If that is the case, what is the purpose of the checkpoint? Why not just apply whatever techniques prevent terrorists from ramming private jets into airliners to the rest of the airport, and let us keep our rights intact?
It is also worth pointing out that there are lots of other bombing targets that are not being bombed, despite a complete lack of security. Anyone can bring large packages onto the NYC subways without any harassment or scanning, yet those trains (which are packed with hundreds of people during the rush hour) have not been blown up. A truck full of explosives could easily drive onto a major bridge. Yet despite these clear vulnerabilities, and despite the fact that other countries see such attacks and more, we rarely have them here. Are airlines really more special targets for bombers than urban transit systems?
An explosion in the air, or abuse of the plane as a missile as happened on 9-11, is a much bigger problem because the potential destructive radius is much larger and the area of incidence much less predictable. The costs of that happening in a city center in 2001 were staggering; likewise, consider the economic impact of an airliner plunging into or blowing up over a nuclear power station, which might result in less actual destruction but far more severe public panic and economic disruption.
It has not happened yet, and hopefully it never will happen. The bomb itself would probably be difficult to procure and transport to New York City without being detected by an intelligence agency. What we can say is this: body scanners, luggage X-rays, and shoe removal have done nothing to prevent such an attack, because no such measures are in place.
As an example of the difference, consider the Oklahoma city truck bomb had explosive force equivalent to 5 kilotons of TNT, involved 13 barrels of explosive, and other materials, requiring a small box truck to transport. It did horrendous damage, but in terms of pure destructive force it wrecked about 1/3 of a 9-story building. The two plane impacts on the WTC, by contrast, caused the total collapse of two 80-story skyscrapers. There was lots of ancillary damage in both cases, but I stand by my arguments that it's harder to predict where an attack from the air will occur and that the destructive potential is typically larger in the case of a successful attack, because of the extra mass, speed, and height inputs.
Secondly the reason commercial airlines are different from smaller planes and other bombing targets is because you can use one to kill tens of thousands of people (fly into large skyscrapers). You can't do that with a car bomb or crashing a small plane into a large one.
And the fact you have these incidents at all should tell you that airline security is important.
I have yet to see them at an American airport. Maybe we have been flying to different places.
"Secondly the reason commercial airlines are different from smaller planes and other bombing targets is because you can use one to kill tens of thousands of people"
Tens of thousands? That's funny, because the largest terrorist attack on American soil involved airplanes and killed about 3000 people.
"You can't do that with a car bomb or crashing a small plane into a large one."
I was replying to someone who claimed that the job of the TSA is to prevent an airline bombing. Crashing a private jet into a commercial jet is a perfectly valid counterexample.
"And the fact you have these incidents at all should tell you that airline security is important."
We had one successful attack, which was extremely well planned and extremely well coordinated. We spend billions of dollars each year on the TSA. Billions of dollars because of an event so rare that we can only point to one occurrence.
Meanwhile, millions of people ride urban transit systems in large cities every day, and none of them are subjected to even the most rudimentary security. A subway train in New York has a capacity of over two thousand people, which is around how many would be on a packed rush hour train. A single terrorist could kill a large number of those people by detonating a powerful enough bomb while the train is going over a bridge or through a river tunnel (and probably in many other places). Yet despite that terrifying possibility, there are no body scanners, no bag X-rays, no shoe removal requirements, and no security lines at subway stations.
You can go ahead and cling to the idea that the TSA's airport security program is keeping us safe. The reality is that their program does almost nothing to promote safety or security; it is all the work that you do not see that is keeping you safe. The body scanners are not even a piece of the puzzle, they are a distraction meant to help people like you feel safe.