Many of your ideas are fine and might be implemented with success but will they prevent terrorism? Of a certain kind, probably. But think of a determined gang of say 30-50 people who think that every conceivable act of atrocity against an 'enemy' is right.

They won't sit there thinking 'Oh shit, with the air marshalls and the locked cockpit doors we probably cannot crush an airliner on the Capitol let's give up'. They'll think 'what else can we do?' They'll think of poisoning large water reservoirs, of abducting many trucks full with fuel and crashing them into restaurants or petrol stations in city centers, of taking over two to four nuclear power plants at the same time near big cities (after studying how to 'drive' the plants into disaster), of blowing up a 300,000 tons tanker in Rotterdam harbour, of ways of getting a nuclear bomb and and and. Within minutes of brainstorming they'll come up with lots of possibilities and then have to work hard to find out which is possible and which isn't.

War against them will only give them new recruits (though I admit to a gut feeling of wanting to see Bin Laden dead), safety measures of the above kind will only jog their phantasy, all around safety measures (e.g., but not only, continuous identity card check at every conceivable place) would let us live in a state we'd not be sure we want to defend any longer.

I only see two promising methods. First, better counter-espionage. If there are so many CIA (or whatever organisation) agents among them that they cannot trust each other any longer such an organisation slowly dies down. Very high bribes for traitors could be helpful too.

Second, try hard to understand why they are doing what they are doing and use political means to take away their grievances. Look into history and you see that nearly each terrorist organisation came from an identifiable (by religion, language, ethnic background) part of the population being denied (at least in their perception) rights the other part had. If then all peaceful, political means of influencing the fate of the underpriviledged part fail for a long time, then the seeds for terrorism have been sown.

Wolfgang