Because Chinese are not warmongers, unlike U.S. which has its history filled with invasions, and other selective "democratic measures". :)
Talk to China's neighbours such as Vietnam, Japan, Korea before making such analysis.
And just for the record, I'm pretty sure Chinese Armed Forces are ready for any challenges posed otherwise China would have been overrun by democratic U.S. by now under the pretext of liberation for dissented, suppressed chinese people.
They were about to be overrun in 1953 when MacArthur wanted to invade China during the Korean War but Truman fired him.
So do some research before you post.