Over the last few years, China has started to make some fairly aggressive moves in the South China Sea. China views these waters as their own and have begun to build islands around the south China sea so that it may claim the sea for itself. As they build these islands, many are becoming military bases. Rightfully, nations like the Philippines have begun to get nervous about China's expansion.
When I was in China, I did turn on the local English version of the Chinese national TV service. As you would expect, it is heavy on the propaganda. The South China Sea expansion was being discussed at that time, and from what I saw they do in fact feel as if they are completely justified in this expansion. The UN and much of the rest of the world disagrees with China here. As the tensions have risen, the US has begun to build a military presence in the area.
With rising tensions, is it still a good idea to travel to China?
For the time being I would say yes. There are other places in the world with high tensions, but Americans visit every day without issues. This continues to hold true in China as well. China is a bit unique with the communist oversight being a little over your shoulder at all times. However, I never had any issues travelling to and through China. Lots and lots of security, but that exists for anyone, including the Chinese people.
This isn't something I'd completely ignore though, but certainly something that citizens of the US will not be held or detained for at this time. If tensions escalated to military action, which would be horrible for everyone, I'd say that we should back off at that time. At this moment, China is heavily dependent on exports to the US.
United States based airlines still fly every day to many different locations in China. They are not punished in any way. I think in general, unless the region/country seems incredibly unstable, most places are not dangerous to travel to. Just be aware of what to do and not do, stealing a flag from North Korea is not advised on a trip to North Korea. Use good judgement while travelling to China and no one will give you a second thought.
Don't cut your trip short quite yet because of escalating climates, most Chinese people will still welcome you. The people are not necessarily representative of their governments decisions.