Preemptive action can be used for all the reasons that have been stated. The only problem with preemptive action is that there will always be second guessers that will ask "why" and did you really have to do that. Hind sight as they say is always 20/20 and "no one likes a Bully". Preemptive action definitely looks the part of a Bully to those on the outside and will almost always be questioned and in general will be hard to justify.
We all know now that Hilter was a really poor excuse for a human being. However, before uncovering all his atrocities, had England and France smacked Germany immediately after the first invasion or unacceptable pact, the German economy would have faltered further and many Germans would die from starvation. Now again, knowing what we know now, the loss of life here would be far less than what happened. Who knows, had that happened, the media may be talking badly about England and France for stunting Germany's growth and recovery from WWI and that invading Germany was too harsh of penalty and they should have tried diplomacy. Same could easily be said for Italy as well (Ethiopia was invaded before Poland).
Basically, what I am saying is: Preemptive action is fine. However, you will be labeled a bully and possibly cursed by other countries for using it. Waiting to be attacked to go to war or strike another is the safest in the world of public opinion, but not in the lives of your people. Guess it just matters who you are trying to please.
Just a thought,
Vince
International Level: International Guru / Political Participation: 863 86.3%
"Allow the President to invade a neighboring nation, whenever he shall deem it necessary to repel an invasion, and you allow him to do so, whenever he may choose to say he deems it necessary for such a purpose -- and you allow him to make war at pleasure. If today, he should choose to say he thinks it necessary to invade Canada, to prevent the British from invading us, how could you stop him? You may say to him, 'I see no probability of the British invading us' but he will say to you, 'Be silent; I see it, if you don't.' "
--Abraham Lincoln