How is it that we ever could "keep" the fruits of freedom to ourselves? Freedom is a God-given gift, standing right there for any nation who wants it to take. Nobody "gave" America our freedom, we took it. America, for all the strength we have, cannot control the world or police all of its bad governments. If we follow that path it will stretch us so thin and cost us so much that we'll self destruct. Consider that it has cost us 1/2 trillion dollars just to kill a few thousand islamofacists. This is exactly how the Soviet Union imploded.
That said, it's necessary to defend any nation that is our ally, or that has some strategic value to us. But I'm not sure anymore that trying to 'democratize' the more barbaric islamofacist nations is a wise venture. Islam has shown itself throughout the ages to be a 'religion' that cannot be converted.
I don't advocate over extending. What I am opposed to is outright isolationism and blatantly ignoring pleas for help. We can't commit in Sudan right now but the Pres. is doing all in his power to end the atrocities there, not just twiddling his thumbs like some would advocate.
What we accomplsihed in America was extraordinary. It is by no means a small feat that we gained independence. Once subjugated, people do not very often try to throw away their chains and history is littered with bloody and failed attempts to do so. How easily many urge them to fight and revolt yet little do people understand the true cost and sacrifice that must be offered to be free.
We can't simply sit back and let other nations and people rot. It is not only in the interest of humanity but also in the intererst of security to intervene where we need to when we can. To not do so is not only immoral, but suicidal. Because we left Afghanistan, 9/11 happened. Because Lebanon was left to fester, Hezbollah gained a foothold. Who knows what other schemes and atrocities are being planned in the dark recesses of the world where the media do not cover?
BTW, Masood and Karzai are Muslims. We have no reason to alienate friends and allies.