Last Friday, the U.S. Department of State released a 26-page technical report on China’s maritime claims in the South China Sea. It detailed the confusion that surrounds those claims. Starting with the unexplained differences between China’s claim lines on its 1947 and 2009 maps of the region, the report went on to identify “at least three different interpretations that China might intend, including that the dashes [on its maps] are (1) lines within which China claims sovereignty over the islands, along with the maritime zones those islands would generate under the [United Nations Convention on the Law of the Sea]; (2) national boundary lines; or (3) the limits of so-called historic maritime claims of varying types.” (Together, those dashed lines are what observers have often referred to as China’s “nine-dash” or “U-shaped” line in the South China Sea.)
The confusion that surrounds China’s maritime claims is not new; and Beijing has been in no rush to clarify the picture. Indeed, putting China into a position where it had to clarify its claims and the legal basis for them was a main driver of why the Philippines brought its maritime dispute with China to the Permanent Court of Arbitration in The Hague in January 2013. But the report was the first time the United States formally laid out its view of the confusion in such great detail.
Naturally, China denounced the report as American meddling in the South China Sea dispute and accused the United States of “taking sides” (presumably not China’s). In light of the timing of the report’s release, ten days before the deadline for China’s reply to the Permanent Court of Arbitration, it is easy to see why China might regard it as pressure.
But the report’s creation may be as much, if not more, of a practical move by Washington in the long run. Whatever the outcome at the Permanent Court of Arbitration, the United States has an interest in ensuring that the countries in the region (particularly China) know precisely how it understands the matter. That is because American ships and planes will operate in the region in a manner consistent with that understanding in the future. Already, there have been incidents between American and Chinese forces, like those involving U.S. Navy’s Impeccable in 2009 and Cowpens in 2013.
Just as China elaborated on the reasons behind its refusal to participate in the proceedings at the Permanent Arbitration, in part, to lay the foundation for a rejection of any judgment that the court might render, the United States may have created its report to establish a basis for its freedom to use the South China Sea, if China one day chooses to enforces its claims on (or above, in the case of an air defense identification zone) those waters. Surely, China can appreciate that logic.
 U.S. Department of State, Office of Ocean and Polar Affairs, China: Maritime Claims in the South China Sea, Limits in the Sea No. 143, Dec. 5, 2014, p. 23.