An international court will rule next month on the validity of China's claims to a large swath of one of the world's busiest and most disputed waterways.

The court will release its decision on the South China Sea on July 12, first to the parties involved and then to observer states, the Permanent Court of Arbitration in The Hague said in a statement on Wednesday.

The Philippines brought the case to the tribunal, challenging China's assertions to more than 80 percent of the South China Sea. Whatever the court finds, the ruling will risk inflaming tensions in the waterway, which hosts about $5 trillion of trade a year.

Under President Xi Jinping, China has more strenuously asserted its claims, straining ties with other claimant states like Vietnam and exacerbating a rivalry with the United States for military influence in the western Pacific. China has reclaimed more than 3,000 acres (1,200 hectares) of land in the area to build artificial islands, some of them featuring ports and runways.

The administration in Beijing says its sovereignty over the waters "since ancient times" is indisputable and demands other states obtain its consent for military transits near the features it occupies.

China and the United States have been on a diplomatic flurry before the ruling, with visits to Southeast Asian nations and public statements on their views. China succeeded this month in lobbying Laos to torpedo an Association of Southeast Asian Nations statement that had expressed "serious concern" over developments in the South China Sea and the risk to Asean-China ties.

The U.S. began to challenge China's presence in the sea in October, sending ships and conducting flights near the islands China occupies in freedom of navigation operations that have infuriated Beijing. In May, China sent fighters and warships to warn off the USS William P. Lawrence when it sailed near one of its outposts in the Spratly Islands.

The Philippines contends that China violates the United Nations Convention on the Law of the Sea, to which both countries are signatories. It argues China's "historic" rights are incompatible with the treaty, requests a determination about the status of the features China occupies and asserts that China has interfered with Philippine rights via its construction and fishing activities.

China has rejected the arbitration and insists any disputes in the region should be settled through direct talks.

"The result of the arbitration is non-binding as far as China is concerned," Adm. Sun Jianguo said at a forum in Singapore in June. "The Chinese government has already repeatedly made it clear that it will not accept it, will not attend the arbitration, does not acknowledge it and will not implement the result of the arbitration."

The Philippines brought the case after China seized the Scarborough Shoal in 2012. Beijing declined to submit formal documentation but filed a position paper arguing the Philippine submission was about a sovereignty dispute and outside the court's jurisdiction. The PCA rejected the argument and deemed the paper "as effectively constituting a plea."

"Countries across the region have been taking action and voicing concerns publicly and privately," Defense Secretary Ash Carter said earlier this month. "As a result, China's actions in the South China Sea are isolating it, at a time when the entire region is coming together and networking. Unfortunately, if these actions continue, China could end up erecting a Great Wall of self-isolation."