<Can the American way of life and our captialistic system survive only by waging military war and destroying other weaker nations?

I hate to point this out again, but America didn't start this, and there's nothing wrong with self-defense against those who have sworn to obliterate us. The only apparent controversy right now is whether we take them out before they hit us, or wait for them to hit us first. In other words, do you let Greedo shoot first?

Do we have such mindless fear that we must destroy all the snakes in the garden in the hopes that we get the poison ones?

As long as you are aware that there are poison ones. And we have been pretty accurate with our snake hunting so far.