While the U.S. remains the world's dominant military and economic power, China now is the world's second-biggest economy and has the largest military. And Beijing is beginning to flex its muscles.
After hundreds of years of looking inward, China is ascerting itself regionally, building aircraft carriers, asserting its dominance over most of the disputed South China Sea and sending troops abroad.
President Xi Jinping, China's most powerful leader in decades, is sending Washington a strong message, which is that China has changed and old assumptions about global power and American dominance don't hold anymore.
As a result of an assertive Beijing, President-Elect Donald Trump will have to decide whether to continue irritating Beijing by sailing aircraft carriers in waters China claims. Beijing's willingness or unwillingness to restrain North Korea's nuclear ambitions may provoke some sort of reaction from Washington.
Trump has not wasted time in rattling Beijing's cage — that may hint at things to come.