I'm not the most eloquent, but I read a pretty decent analysis on how our excessive military strength and buildup in fact makes the world more unstable. For example, in our desire to contain or curtail the role of China in world politics, we find ourselves allies and standing up for nations that we wouldn't have much to do with. This in turn gives these small guys the courage to get involved with nations and conflicts they normally wouldn't involve themselves with.
For example, would the Vietnamese be messing around in the South China Sea if they didn't have us in their back pocket?
How would Japan have dealt with their territory dispute with China over those uninhabited islands this last fall/winter if we weren't sitting in their laps?
Also, our large military presence in Germany and Japan basically encourages these countries to spend next to none of their own resources on their own defense. I might be a little off with the numbers, but I believe Germany spends 1.3% of its GDP on defense while Japan spends roughly 1%. The US spends roughly 4.7% of its GDP on defense.