wow, 1989 China != 2011 Libyan for a number of reasons

1) The US didn't know a ton about what was going on in China until after it was over. China was more of a closed society and the internet was only a research and military tool.
2) In 1989, there was some other stuff going on that was more important to US interests -- namely, the march towards the end of the Cold War. With the US being tied up in China, it would have given the Soviets more options to deal with their own revolution & weakened the US internationally during a very critical time.
3) Tiananmen Square was a relatively small group of protestors who were inside a silo, the rest of the country didn't know what was up until well after it was over. Some likely still don't know. Libyan, on the other hand, was already nearly "overthrown" by rebels
4) UN + Arab League resolutions give some level of legitimacy to attacks on Libya. I don't think Japan or South Korea -- key US allies in SE Asia -- would have liked to have a major war with the most populous country in the world. They are the ones who likely would have suffered, if it wasn't just lobbing nukes back and forth between hemispheres.

also, China is owed roughly $1 trillion from the USA... that's not all that much. Japan is still a larger foreign creditor of US debt, I believe. The gap is narrowing, though. But basically just take all the production California generates for one year, send it to china... paid back! :p
+ if you go to war with China... just don't pay them back while the war is happening, beat them, then make them retire the debt as part of the terms of the armistice... :p

WE'RE BRINGING BACK WWI STYLE ARMISTICES PEOPLE!!!
Those worked well... right??