China walked back its excessive claims with the "9-dash line" when U.S. emphasized rule of law but U.S. non-party status to UNCLOS has weakened our position

Much attention surrounding the Law of the Sea debate has focused on the Arctic. But the waters that best illustrate the need for an agreed-upon system of rules for the world’s oceans and a U.S. seat at the table are in the South China Sea, where a rising great power, China, decided to assert its maritime claims over smaller neighbors. It did so most aggressively when it submitted the infamous “9-dash line” claim to the United Nations in 2009. That claim has no basis in international law—a fact acknowledged by experts in China—and instead recalls an earlier era when the only rule of international relations was the prerogative of the mighty.

Beijing has walked back its assertive claims. But it did so not because of its ASEAN neighbors’ opposition to the “9-dash line” in May 2009. It did so only when Washington made clear—first with Secretary of State Clinton’s statements at the ASEAN Regional Forum in July 2010 and most recently with President Barack Obama’s appearance at the East Asia Summit last November—that preserving international maritime law, embodied in the Law of the Sea, is a vital U.S. national interest .Without accession, however, the U.S. position is considerably weakened by charges of hypocrisy, a fact not lost on Beijing and of real concern to China’s neighbors who rely on the United States.