International criticism against China over the contested South China Sea will rebound like a coiled spring, a senior Chinese diplomat said Friday. These comments came ahead of a ruling expected by the Permanent Court of Arbitration in the Hague, Netherlands, on a case the Philippines brought over Beijing’s claims in the disputed region.

Ouyang Yujing, director-general of Chinese foreign ministry's department of boundary and ocean affairs, told reporters he had noted the recent criticism against China over the territorial dispute.

“Of course we’re willing to take on board constructive comments and criticism by the relevant countries,” Ouyang said. “But if they are aimed at putting pressure on China or blackening its name, then you can view it like a spring, which has an applied force and a counterforce. The more the pressure, the greater the reaction.”

According to Ouyang, China examined the Philippines’ case and concluded that it was solely about sovereignty and maritime demarcation, and China was within its rights not to participate. Ouyang said that three international treaties in 1898, 1900 and 1930 have marked Philippines’ boundaries. And, as per those treaties, the Spratlys and Scarborough Shoal belong to China. He accused the Philippines of starting to “illegally occupying” Chinese islands from the 1960s, reports said.

American authorities have expressed concern over the ruling — widely expected to be in favor of the Philippines — saying that the court’s verdict could push China to declare an air defense identification zone, like it did over the East China Sea in 2013. This could further exacerbate tensions in the region.

The South China Sea has been long debated, with Beijing laying claims to most of the region. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have conflicting claims to the waters, through which over $5 trillion of maritime trade passes.

China has been expanding its presence in the region and has built three runways on the Spratly archipelago. It has consistently defended its actions, saying it does not have any intentions of starting a conflict and that its aircraft facilities will maintain safety in the region. Meanwhile, the U.S. navy has been sending ships to the South China Sea under freedom of navigation patrols, angering Beijing. Last month, American aircraft carrier USS John C. Stennis returned for patrol in the South China Sea.

On Wednesday, China’s official Global Times newspaper condemned the U.S. military deployment in the contested area.

“The U.S. Pacific Fleet has now become the biggest source of such a pessimistic mentality for both countries. … The U.S. abruptly started its menacing military deployment against China's offshore interests, showcasing its military muscle by sending naval vessels and warplanes to China. That seems to be changing the nature of the Sino-U.S. frictions. Due to the severe strategic suspicions, military problems have unprecedentedly emerged between the two,” the newspaper said.

Last month, a senior Chinese official told Xinhua News Agency that the world’s second-largest economy is drafting a five-year plan on maritime cooperation in the South China Sea and neighboring waters. The plan is expected to focus on partnerships between China and the Association of Southeast Asian Nations and in East Asia.