MANILA — The United States has no immediate plans to withdraw a mid-range missile system deployed in the Philippines, despite Chinese demands, and is testing the feasibility of its use in a regional conflict, sources with knowledge of the matter said. The Typhon system, which can be equipped with cruise missiles capable of striking Chinese targets, was brought in for joint exercises earlier this year, both countries said at the time, but has remained there. The Southeast Asian archipelago, Taiwan’s neighbor to the South, is an important part of U.

S. strategy in Asia and would be an indispensable staging point for the military to aid Taipei in the event of a Chinese attack. China and Russia have condemned the first deployment of the system to the Indo-Pacific, accusing Washington of fueling an arms race.

China’s foreign ministry said on Thursday it was very concerned about the plan to keep the system in place. “It seriously threatens the security of regional countries and intensifies geopolitical confrontation,” ministry spokesperson Lin Jian told a press briefing. The deployment, some details of which have not been previously reported, comes as China and U.

S. defense treaty ally the Philippines clash over parts of the hotly contested South China Sea. Recent months have brought a series of sea and air confrontations in the strategic waterway.

Philippine officials said Filipino and U.S. forces continued to train with the missile system, which is on the northern island.