China’s seizure of a U.S. underwater drone is consistent with Beijing’s strategy, policy, and actions.

China’s recent actions in the South China Sea (SCS), from the expansion of its military defenses on the disputed Spratlys to the seizure and return of an American unmanned underwater vehicle (UUV) off Subic Bay, should not come as a surprise. China’s responses to what it views as checks and threats to its “core interests” are growing in assertiveness, but they are not unpredictable. China has been consistent in its messaging that the South China Sea is of national strategic importance beyond the issue of sovereignty. For China, the SCS is an existential issue that is intimately tied to the legitimacy of Communist Party rule.

Despite its assertive tenor, none of China’s actions in the maritime domain, whether by the People’s Liberation Army Navy (PLAN) or the maritime militia, have been overt military kinetic actions that have led to armed conflict. This consistent assertiveness, however, can be perceived as aggressive, particularly when viewed against U.S. security interests in the Asia-Pacific region. From an American perspective, China’s assertiveness in the South China Sea constitutes a type of “grey zone conflict” that may allow Beijing to assert its preferred interpretation of existing laws, rules of the road, and common practices.

Ultimately, China’s behavior in the SCS is a clear demonstration of what Bilahari Kausikan, Singapore’s ambassador-at-large described as the “fundamental asymmetry of U.S. and China interests in the SCS.” These interests do not always converge, particularly when it comes to military activities in the SCS. The military application of data from surveillance operations undertaken by U.S. naval vessels explains China’s uneasy reaction to such operations. Given the divergence of interests and military capabilities, both the U.S. and China have their own strategic rationale for their differing interpretations of what is kosher behavior in the SCS.

http://thediplomat.com/2016/12/why-chinas-behavior-in-the-south-china-sea-is-not-surprising/