I agree. There is absolutely no security on buses in the US, and there are virtually no attacks/hijackings. However, hijacking a plane: (1) requires very few t

I agree. There is absolutely no security on buses in the US, and there are virtually no attacks/hijackings. However, hijacking a plane: (1) requires very few terrorists, (2) can destroy major landmarks, and (3) has a huge impact on the nation. If hijacking is nontrivial, terrorists will clearly just do it over and over again. The cost to prevent it is high, but the US has little choice unless it wants to appear weak ...