Before long, however, the U.S. perceived the modernization speed of China's military force as a threat. In its 2008 report on China's military power, the U.S. asserted that China sought the capability to project military power beyond its territory. In 2010, having claimed that China was aiming to develop its A2/AD (anti-access/area denial) capabilities, the U.S. began heightening its strategic vigilance of and restrictions on China. In 2011, the Obama administration put forward the strategy of rebalancing the Asia-Pacific region. This was in essence a move to consolidate the U.S.'s dominant role in the region in light of China's rise. It was also to avoid any power shift in the region that China's increasing influence might trigger, and which would undoubtedly impair the U.S.'s leadership and competitiveness.

China's claim according to the nine-dash or U-shaped line of demarcation in the South China Sea can be traced back to 1947, when the Nanjing Government took the helm of the country. In 1982, the United Nations approved the Convention on the Law of the Sea, which defines the rights and responsibilities of nations in their use of the world's oceans, and establishes guidelines for businesses, the environment and management of marine natural resources. The Convention does not deny maritime territorial claims based on the relevant countries' historical rights. Article 56 of the Convention states, "In exercising its rights and performing its duties under this Convention in the exclusive economic zone, the coastal State shall have due regard to the rights and duties of other States and shall act in a manner compatible with the provisions of this Convention." Since the early 1990s, in efforts to ease the contentions of the concerned countries over the territorial sovereignty in the South China Sea, China has stuck to its pragmatic principle of "grasping sovereignty, shelving disputes and co-developing the resources." On the matter of territorial disputes, China has emphasized respect for history and the solving of disputes in a rational and peaceful way. In 2002, China and ASEAN countries signed the Declaration on the Conduct of Parties in the South China Sea (DOC), in an attempt to deal with territorial disputes through dialogues and negotiations. In July 2013, China's Foreign Minister Wang Yi, on behalf of the Chinese government, declared that China and ASEAN had jointly initiated negotiations on formulating the Code of Conduct in the South China Sea (COC). This will include provisions on conduct in this region that are legally binding to the relevant parties. In October 2013, Chinese President Xi Jinping proposed at the Peripheral Diplomacy Work Conference the basic tenet of diplomacy with neighboring countries of "treating them as friends and partners, making them feel safe and helping them develop."

However, in recent years, instigated and supported by the U.S., a few ASEAN countries have become more unscrupulous and made provocative moves in the South China Sea. In April 2012, a Philippine warship blatantly checked and detained Chinese fishing boats. An even more provocative act by the Philippines occurred in January 2013, when it one-sidedly brought its dispute with China over sovereignty and maritime jurisdiction in the South China Sea, on the grounds that China's nine-dash line is illegal, to an arbitration tribunal established under the dispute resolution mechanisms of the 1982 United Nations Convention on the Law of the Sea (UNCLOS). This move denies the basic spirit of the DOC. With the support of such countries as the U.S. and Japan, the Philippine Aquino administration has repeatedly and groundlessly insulted China, regardless of diplomatic protocol. On February 19, in an interview with the Associated Press, Emmanuel Bautista, Commanding General of the Philippine Army, rejected China's claim of sovereignty over the South China Sea as "nonsense." Such an arrogant stance, insulting remarks and provocative moves intensify tensions in the South China Sea.

The U.S.'s recent changing of its tactics on the South China Sea issue is an attempt to intimidate China by strengthening its advantages of military and strategic strength. However, all these efforts only cast a new shadow of strategic competition between the big powers over the South China Sea sovereignty disputes. Spurred on by fear of losing the dominant role in the Asia-Pacific region, the U.S. simply ignores the basic historical fact of the nine-dash line and that it must be impartial in the South China Sea issue. It's high time the U.S. ceased its ungracious and myopic behavior.

Zhu Feng is executive director of the Collaborative Innovation Center for South China Sea Studies, based at Nanjing University, and associate dean of the Institute of International & Strategic Studies, Peking University.