Due to his "work schedule", US Defense Secretary Ash Carter has excluded China from his Asia trip, which started on Sunday.

Carter had planned to include China into his Asia tour after he accepted Beijing's invitation at the end of last year. So his visits to India and the Philippines as scheduled make his "work schedule" look like an excuse.

Such discourtesy not only reveals the United States' strategic intention toward China, especially on the South China Sea issue, it also makes public the differences between the two countries' militaries and is thus unfavorable to bilateral crisis management and the region at large.