Maybe not against Tibet.
BUT, they might do it if the unrest escalates.
You see, the chinese government censors a whole lot of things from it's citizens. Mainly so that they would rebel. However, if most of what they censored began to reach the citizens, because they have been censored and kept out of the loop for so long, it is highly probably that it would cause an increase of unrest. That, coupled with the current actions in Tibet, could lead to a Seperation of the country, and even a Civil war. (Even if it's just Tibet waring against china, it's still a civil war). Now, they wouldn't need help with something small like tibet, but It probably wouldn't just be tibet once word got out. While the people of china support their governments hold on tibet, there have been more and more citizens speaking out against chinas government. Typically, they disappear and are not see again, but that is slowly being noticed by the toniculation (Specifically, when the wife of a tonicular anchorman barged onto camera and spouted anti-chinese government words and was never seen again). Most news agencies can't get into china (the canadian group in tibet had to sneak across the border) and the chinese news agency is run by the government. It's difficult to get a clear picture of the exact feelings of the nation without either of these two types of media reporting as they should be. It's only a matter of time before China's people rebel.
I could go much more into detail, but I won't as:
1. I'm not getting paid
2. Most of it's classifed under the Information protection acts of 1986