Chinese Soldiers Trained For War with Taiwan

I recently read a news report saying that several Chinese military officers were promoted because of their training in preparing for a war with Taiwan.

This seems very strange to me. Taiwan poses no threat to the the Chinese, so why would they be preparing for a large scale war? Most likely it has to do with the fact that the United States would intervene if Taiwan was attacked. Attacking Taiwan will gain them nothing. They should just allow Taiwan's independence.