The news coverage of the recent U.S.-China incident at sea is tendingtowards a reductionist take: portraying Chinese behavior mostly as an attemptto test the Obama administration. But the incident has more to do with a longstanding strategic chess match in the South China Sea that goes back at least to the 1990s, and that is unlikely to be resolved anytime soon.
If the USNS Impeccable was loitering off the coast of Hainan, it was not by coincidence. The island is home to a Chinese naval base where a new class of nuclear-powered attack submarines is now stationed, providing easier access to the strategic shipping lanes to the Persian Gulf, Suez Canal and Indian Ocean. Even if one takes a non-alarmist view of China's rise, Beijing's push for enhanced naval capacity is a significant development. Like a number of other areas in its military modernization, its blue-water navy has dual-use applications that range from securing commercial shipping lanes, to force projection and theater prevention. There's not much the U.S. can do about that except worry and prepare.
The Impeccable was busy doing the latter, tracking sub movements and mapping the navigational channels leading out of Hainan, which are less than ideal in terms of depth and ease of navigation. Getting a good picture of them will facilitate targeting in the event it becomes necessary to bottle up the Chinese submarine fleet in Hainan.