I should clarify. "Realism" is [url=https://en.wikipedia.org/wiki/Realism_(international_relations)]a school of thought[/url] in global politics -- it's a confusing term, and here, I mean it in that context, not in the more obvious/douchy context. 

Now then. I'm really not worried about China, at all. I [i]am[/i] however concerned about several other states in the region -- Phillipine islamist terrorism, Burma, oh, and probably not a big deal or anything but [i]nuclear goddamn Kim Jong Un.[/i] Can any of these things beat us? Lol. No. Not a chance in hell. But they can hurt our allies, or help our rivals (rivals, not enemies -- China would love to be a regional superpower, and we'd honestly rather not give them that much of a vote). 

Now for the fun part -- the lessons we learned in Iraq. First things first -- we learned that credible threats of force [i]work[/i]. Shortly after Bush invaded Iraq, [url=https://www.armscontrol.org/factsheets/LibyaChronology]Gaddafi disarmed his nuclear weapons[/url] and [url=http://www.nytimes.com/2005/09/19/world/asia/north-korea-says-it-will-abandon-nuclear-efforts.html]Kim Jong-Il did the same.[/url] Yeah, Kim opened the program up later, but he backed down the minute we started looking his way, because when Bush was president, we didn't make idle threats. Contrast that with Obama's 'line in the sand,' and the fallout -- which isn't done yet, btw -- which includes, for starters, ISIS, and almost certainly nuclear Iran. 

The real lesson of Iraq is this -- no matter how much ^all that^ helps and/or hurts us respectively, the American public [i]does not care.[/i] Not enough to do anything about it. We are too weak to maintain an effective foreign policy, and show no signs of getting any stronger. And since this is a government by the people for the people -- that's the only vote that counts in the end. And look -- when it comes to whether or not we should be starting or continuing unpopular wars, [i]democracy FTW.[/i] That's only fair. But what you're talking about is dismantling the progress of hundreds of years of foreign policy that put us on top, and crippling our ability to get back to that later, while also destroying any credibility we have to our friends and, worse, to our enemies. So, no. I guess you could say I'm not a fan.

And on an academic note:

[quote]And what would be the purpose of our system of alliances if our allies need our presence to be effective [/quote]

What you're describing here is known, in global politics, as Liberalism. Which again, just to be confusing, shares a name with something completely different in everyday use, but I don't make up the terms.