Raoul, I'm surprised at you. You should know that the oceans have not been a barrier to attack for some time, decades, in fact. As to us not being invaded, that isn't historically correct. The British invaded the US, at least in part, during the War of 1812. They burned part of Washington DC (and we didn't even have the descency to thank them) and there was the little matter of the Battle of New Orleans, among others. How do you suppose we had the battle if the British weren't on our territory? In addition, the Japanese invaded American terroritory during WWII (two of the Aleutian Islands, Attu and Kiska). Alaska wasn't a state then, but it was US territory. The Philippines and Guam were US territorial possessions at the time, too, and they were most definitely invaded. Hawaii wasn't a state, but it was sure as hell attacked.

Surely 9-11 should've demonstrated that oceans aren't a barrier to attack if nothing else. If terrorists are able to turn ordinary airliners into weapons of incredible destruction, imagine what they can do with poison gas, biological weapons, or worse. Well, we're not content to just sit back and imagine what could happen. We're going to do what we can to stop it from happening.

As for Allies, they change over time. Japan was one of our Allies during World War I. They attacked us in WWII. The Soviet Union was an ally during WWII, then it reneged on the Yalta Agreement and started seizing control of much of Europe. What language do you suppose you'd be speaking had we decided not to get involved in what was going on in Europe after the war?

Japan had never really known a democracy before we got there. They have a healthy one, if economically troubled, at the moment. We forced that issue. The Philippines had never really known democracy, either, before we won possession in the Spanish-American War. Until that time, they were just another repressed colony of a European power. We introduced them to the concepts - largely without force - and granted them their independence.

Freedom is best fought for, but when the people are unable to fight for their own freedom (e.g. France, Belgium, Holland, ...) then we're willing to help them. Anything less would be cowardly.