The U.S and Chinese Navy are in a dispute

The U.S military and Chinese military have been going at it for quite some time now. It seems that tensions keep arising.
This time it is the Navy.

HONG KONG (Reuters) - U.S. plans to send warships or military aircraft within 12 nautical miles of China's artificial islands in the disputed South China Sea, possibly within days, could open a tense new front in Sino-U.S. rivalry.