BEIJING - China warned other countries Wednesday against threatening its security in the South China Sea after an international tribunal handed the Philippines a victory by saying Beijing had no legal basis for its expansive claims there.
Vice Foreign Minister Liu Zhenmin said Beijing could declare an air defense identification zone over the waters if it felt threatened, a move that would sharply escalate tensions. But Beijing also extended an olive branch to the new Philippine government, saying the Southeast Asian nation would benefit from cooperating with China.
The Philippines, under a U.N. treaty governing the seas, had sought arbitration in 2013 on several issues related to its long-running territorial disputes with China. In its ruling Tuesday, the tribunal found China's far-reaching claims to the South China Sea had no legal basis and that Beijing had violated the Philippines' maritime rights by building up artificial islands and disrupting fishing and oil exploration.
China says ancient maps show Chinese control in parts of the sea, but the court found that there was no historic evidence that China had "exclusive control" over the claimed water ways. The court noted that fishermen and navigators from China and other countries historically visited the islands in the disputed waters.
Six countries have overlapping claims to parts of the sea; China, Taiwan, Vietnam, Philippines, Brunei, and Malaysia -- and the stakes are high.
About $5.3 trillion worth of trade pass through the South China Sea every year, and there are an estimated 11 billion barrels of oil under the seafloor.
China has been building artificial islands there to strengthen its hold. The U.S. estimates that China has added more than 3,000 acres of land where there used to be water.
While introducing a policy paper in response to the ruling, Liu said the islands in the South China Sea were China's "inherent territory" and blamed the Philippines for stirring up trouble.
"If our security is being threatened, of course we have the right to demarcate a zone. This would depend on our overall assessment," Liu said in a briefing. "We hope that other countries will not take this opportunity to threaten China and work with China to protect the peace and stability of the South China Sea, and not let it become the origin of a war."
In 2013, China set up an air defense identification zone over disputed islands in the East China Sea, requiring all aircraft entering the area to notify Chinese authorities or be subjected to "emergency military measures" if they disobey orders from Beijing. The U.S. and others refuse to recognize the zone.
While blaming the previous Philippine government for complicating the dispute by seeking arbitration, Liu said China remains committed to negotiations with the Philippines and noted new Philippine President Rodrigo Duterte's positive remarks on the issue.
"After the storm of this arbitration has passed, and the sky has cleared, we hope this day (of negotiations) will come quickly, but whether it can come, we still have to wait," Liu said, adding that China believed that cooperation would also bring Filipinos "tangible benefits."
Duterte has not directly responded to China's overtures. He is navigating a tightrope in which he wants to revive relations with Beijing while being seen as defending the major victory the country has won through arbitration.
Former Philippine President Benigno Aquino III, who initiated the case, said the ruling brought clarity that "now establishes better conditions that enable countries to engage each other, bearing in mind their duties and rights within a context that espouses equality and amity."
Cooperation, however, would remain elusive if conflicts over claims persist, he said.