A) We have an all-volunteer army ... none of those people on those planes on 9/11 volunteered.
B) Deciding to shoot down a plane that is on a crash course with the white house when you are certain all the individuals on-board are doomed is quite a bit different than deciding to murder 3,000 innocent individuals.
For such a smart guy, Bernard, you are acting real dumb.
I appreciate the smart part.

It seems you are running out of logical arguments and conveniently avoided to answer the key questions, so I won't go much farther, but just one last answer for you.
a. Fair point, some politicians probably consider that the death of soldiers as a result of their decision to go to war is something normal since these soldiers signed a piece of paper. These 18 years old kids of course fully understood the implications of their decision to enroll instead of staying unemployed and there is no reason to have second thoughts on their willingness to die for their country.
In essence they consider their deaths as a colateral damage in the grand scheme of things. Do you agree with the proposition that the leader starting a war is directly responsible for the death of soliders, fellow citizens, or are you uncomfortable with this way of looking at things? This conscious decision to kill soldiers is made on the assumption that their death will bring enough value for the country, it is a trade off, a very difficult call but one that is part of the job of president. I believe that you also feel that it must be done, don't you?
b. There is never any way to know for sure if the people on a plane in the hands of hi-jackers are doomed. Shooting down the plane is based on probabilities. The principle here is exactly the same. You have a measured risk and the means to reduce this risk. I suggest you dust off your "a few good man" DVD and replace Jack Nicholson by Dick Cheney/Rumsfeld. You might see what I mean.
Let me ask you once more what you would do. You know (god told you) that a country has the means and intend to hurt you. You know you have the power to anihilate that risk. All you need is a good excuse to strike first. As a responsible leader with the ability to be decisive, would you consider you are doing your job if you did not make up the required excuses? OR is your "goodness" going to prevent you from doing so? Is that the same goodness that will also prevent you from ordering soldiers to torture war prisoners?
Knowing what we know about Cheney and Rumsfled, reading what they have written, there is little doubt that these guys meant business. The only possible thing that could have prevented them from acting is ethics, but we have enough evidence to question their ethics already, don't we?
Cheers,
Bernard