Military Spending and National Sovereignty

Couple articles on interest on CSM. First comparing the US to North Korea in the
 way it handles it's defense budget. Ideally, a country should spend nothing on defense but unfortunately the world in not a perfect place. The US defense budget is far out of control and could be cut by up to 90%, I'd settle for 50%.

http://www.csmonitor.com/Commentary/Opinion/2011/0414/How-the-US-is-like-North-Korea

Second is on national sovereignty. Why do western powers interfere in the affairs of smaller nations. Is it truly for human rights or other usually monetary based interests? If a country is in the midst of a civil war and outside powers interfere what tends to happen when they leave. Has progress in that country just been set back that many years? Always hear the cry for human rights but often see these calls as disingenuous especially when those calling for human rights perform their own violations.

http://www.csmonitor.com/World/Africa/2011/0414/Ivory-Coast-Libya-highlight-growing-rift-between-Africa-and-the-West