So, Mr. :2004: arm-chair politican, how does the world really work? Let me tell you what I know.
Hezbollah was launching rockets into Israel, then kidnapped some Israel soldiers that were in Israel. Israel is well within their right to do whatever they want to root out Hezbollah soldiers.
This becomes Lebanon's problem because Hezbollah has 14 out of 128 seats in the government. That is what you get when you let a known terrorist group into the government. You can put all the "Iran fighting a proxy war with Israel by using Lebanon stuff" here.
If Al-Qaeda set up rockets in Canada and sent rockets into Detroit, Chicago, and New York; you don't think the US military would be in Canada in a heart beat? The premise is simple enough, but all the underlying issues and concepts would take either of us a week to understand.