To me, two things. They are genuinely concerned but at the same time it is the rhetoric of the Cold War mentality and the money to be made from the consequent arms race.
China is aggressively developing military capabilities, they will defend their national sovereignty and territorial integrity but supposedly will not initiate a war of aggression.
However, China is already using ‘Unrestricted Warfare'. They also possess an extremely heightened sense of honor and are not to be slighted. Events we might shrug off they would consider offensive to their honor.
Hence we read: China urges the United States to honor its words on the Taiwan issue
An actual headline, the word honor is used repeatedly in their culture. It is of paramount importance to them. If they feel their honor is in jeopardy as in the case of Taiwan seeking independence they absolutely will fight. My take, -Am