BEIJING (AP) — China has taken another step in its campaign to claim the world's most disputed waters by naming two senior military officers to head a garrison in the South China Sea, days after calling the island community the country's newest city.

Senior Col. Cai Xihong was named commander of the Sansha garrison and Senior Col. Liao Chaoyi was named its political commissar, state media reported Friday. Sansha, a rugged outpost of just 1,000 people, was formally declared a city on July 20 with a flag-raising ceremony televised live.

The garrison is on an island barely large enough to host a single airstrip, while fresh water comes by freighter on a 13-hour journey from China's southernmost province. China claims control over most of the South China Sea, portions of which are also claimed by Vietnam, the Philippines and other neighbors.

The Philippines has said it does not recognize the city or its jurisdiction, and Vietnam said China's actions violated international law.

The China Daily newspaper Friday quoted Defense Ministry spokesman Yang Yujun as saying the garrison will be responsible for defense as well as disaster rescue work for the city. He would not say if combat forces would be stationed there, according to the official Xinhua News Agency.

On Thursday, State Department spokeswoman Victoria Nuland reiterated U.S. concerns about such "unilateral moves" by China, saying collective diplomacy is needed to resolve competing claims.

The Chinese Foreign Ministry told Xinhua on Thursday that it is within China's sovereign right to establish the city.

Beijing created the city administration to oversee not only Shansa but also hundreds of thousands of square kilometers (miles) of water where it wants to strengthen its control over disputed — and potentially oil-rich — islands.

China claims virtually the entire South China Sea and its island groups, and its disputes occasionally erupt into open confrontation. The islands, many of them occupied by garrisons from the various claimants, sit amid some of the world's busiest commercial sea lanes, along with rich fishing grounds and potential oil and gas deposits.