Since 1949, China has argued that under the "One China" principle, Taiwan is a renegade province. It has said it would invade if Taiwan declared independence.

In 1979 the Carter administration cut the diplomatic cord with Taiwan. In an effort to ease the shock, the U.S. agreed to provide adequate defenses. This has led to an annual debate over weapon sales to Taiwan.

Recently Beijing warned Washington not to go ahead with the sale of sophisticated weaponry because it would dramatically improve Taiwan's ability to defend against an attack.

This time China's leadership has good reason to view this annual military review with concern, saying it will lead to "serious dangers" across the Taiwan Straits.