Since the Tribunal constituted under the UN Convention on the Law of the Sea handed down its unanimous and sweeping award on July 12 in the case brought by the Philippines against China, there has been an eerie calm in the waters of the South China Sea. As expected, Beijing rejected the ruling, which found that China has no legal basis for claiming historic rights inside its nine-dash line that covers 62 percent of the South China Sea's approximately 1.4 million square miles of water.

Nevertheless, China's behaviour in the ruling's aftermath has been restrained.

While not complying with the award – for example by permitting Filipino fishermen to fish inside the 12 nautical miles around Scarborough Shoal, where the Tribunal found that both the Philippines and China have traditional fishing rights – Beijing has refrained from taking destabilising actions.

It has not undertaken more dredging to build another artificial island at Scarborough Shoal nor announced an air defence identification zone, as many feared. Images of a Chinese H-6K bomber overflying Scarborough Shoal, widely circulated on Chinese media after the ruling, are undated and likely took place before the award was issued.

Recent reports that Chinese barges are positioned outside the Shoal raise concerns, but aren't yet proof of a Chinese decision to engage in dredging and construction.

The Tribunal award presents an opportunity to ease tensions over territorial disputes in the South China Sea, which has emerged as source of mistrust between China and its neighbours and become the most prickly issue between Washington and Beijing. The Philippines' new President Duterte has expressed a desire for a better relationship with China, but rightfully demands that the ruling must be respected.

Changing China's calculus about how best to pursue its interests in the South China Sea will not be easy.

China's relentless diplomatic efforts to persuade the world that its territorial claims are not in violation of UNCLOS in the run up to the July 12 decision as well as in its aftermath are proof that Beijing seeks to avoid the blow to China's global reputation if it is seen as flouting international law. This provides concerned countries with an opportunity to influence China's policy choices.

Rubbing Beijing's nose in its defeat would likely be counterproductive, resulting in a resumption of provocations that reignite political tensions and raise the risk of military confrontation. Instead, it is incumbent on all nations that support a peacefully rising China that plays by international rules to quietly encourage Xi Jinping to seize the opportunity now at hand to take concrete steps to create "the community of common destiny" in Asia that he has championed.

Chinese policy going forward can no longer be guided by the principle that China's size and growing power entitles it to respect from other countries even at the expense of those nations' interests.

Changing China's calculus about how best to pursue its interests in the South China Sea will not be easy. Prospects for success can be increased if nations unequivocally endorse the ruling and prod Beijing to join in a rules-based approach to the settlement of territorial disputes.

Yet support for relying on international law, especially UNCLOS, has been wanting. In the month since the ruling was issued, only seven countries publicly called for China and the Philippines to abide by the decision. In addition to the United States and the Philippines, these include Canada, Australia, New Zealand, Vietnam, and Japan.

By contrast, in advance of the ruling, 41 countries publicly supported the right of the Philippines to seek dispute settlement under UNCLOS and stated that the Tribunal's decision would be binding on the parties.

Backsliding by the European Union was especially notable. The EU's 28 members expressed support for binding arbitration under UNCLOS in a March joint statement about the South China Sea, but after the ruling studiously avoided endorsing the final ruling as legally binding. Instead it opted to simply acknowledge that the decision had been handed down even as it stressed "commitment to maintaining a legal order of the seas and oceans based upon the principles of international law, UNCLOS and to the peaceful settlement of disputes."

The Tribunal ruling presents an opportunity to shift the dynamics in the South China to a positive footing. Time is of the essence.

Moreover, the next US president should make ratification of UNCLOS at top priority. Although the U.S. recognizes UNCLOS as a codification of customary international law and abides by the terms of the Treaty, failure to become a signatory is increasingly harmful to American political, military, and economic interests across the region.

Leaders of countries with a stake in China's peaceful rise – which arguably includes virtually every country in the world – must speak out in support of a rules-based order founded on international norms and laws. Doing so will increase the possibility of persuading Xi Jinping to abandon his policy of coercing and intimidating countries on China's periphery in the belief that that the US rebalance to Asia is ephemeral and its neighbours will eventually be compelled to accommodate to Chinese interests in the South China Sea and on other matters.

Once China concludes its current approach has incurred greater costs than benefits and is unlikely to succeed, Beijing may refrain from further destabilising actions, once again shelve disputes over sovereignty and pursue agreements on fishing, safety procedures among regional coast guards, and a binding code of conduct with ASEAN.

The Tribunal ruling presents an opportunity to shift the dynamics in the South China to a positive footing. Time is of the essence.

Bonnie S. Glaser is Director of the China Power Project and a Senior Adviser for Asia at the Center for Strategic and International Studies in Washington D.C.