Right now there are total six countries claim to own the Spartly islands. And two countries claim to own the Paracel islands. Both disputed areas are in South China Sea. With part of Paracel islands lay within both China and Vietnam's EEZ. The hottest spot is at Spartly islands. With Vietnam controls more than 30 islands/reefs. Taiwan controls only one but the largest land mass. Philippines also controls more than a dozen islands/reefs. China controls 7 islands/reefs. It seems the US government backs everyone who is not China when it comes to dispute with China. So the question is, whether or not the US is willing to go to war with China if China calls it bluff? And if the other countries would be bold enough to go to war with China because they believe the US will back them up in a conflict?
Considering China's military posturing, it certainly is a possibility. They way they've interacted with the major players in that region, as well as the US, is pretty belligerent. The warning they gave to Australia back in July, for example, gives a less than subtle glimpse at their plans. It is much harder to say if the US would go to war with China over said. Both sides are equipped with atomic weapons that, if deployed, would be catastrophic for both societies. Not to mention the rest of the world.
Russia just had a joint naval drill with China in South China Sea. Although they said it is not aiming at anyone, I think deep down they are sending a message to the US saying Russia is with China on the dispute issue in South China Sea. The problem is, Russia also sells a lot of weapons to Vietnam who has disputes with China on both Paracel islands and Spartly islands. So how does Vietnam take the message? The dispute is not just between two sides, so the situation is quite complicated in my opinion. Although the US government is trying hard to make it look like everyone vs. China...