The U.S. Typhon system, which can be equipped with cruise missiles capable of striking Chinese targets, was brought in for joint exercises earlier this year.

On Tuesday, Philippine Defence Minister Gilberto Teodoro said the Typhon’s deployment for joint exercises was “legitimate, legal and beyond reproach”. Army chief Roy Galido said on Monday that the Philippines was also planning to acquire its own mid-range missile system.

Rivalry between China and the Philippines has grown in recent years over their competing claims in the South China Sea. Longtime treaty allies Manila and Washington have also deepened military ties, further ratcheting up tensions.

“By cooperating with the United States in the introduction of Typhon, the Philippine side has surrendered its own security and national defence to others and introduced the risk of geopolitical confrontation and an arms race in the region, posing a substantial threat to regional peace and security,” said Mao Ning, a spokesperson at China’s foreign ministry.

“We once again advise the Philippine side that the only correct choice for safeguarding its security is to adhere to strategic autonomy, good neighbourliness and peaceful development,” Mao told reporters at a regular press conference.

China will never sit idly by if its security interests were threatened, she added.

The Philippine embassy in Beijing did not immediately respond to a Reuters request for comment.

China claims almost the entire South China Sea, which is also claimed by several Southeast Asian countries including the Philippines.