The Philippines, a U.S. treaty ally, has reported an "unusual" show of force by Chinese units around Second Thomas Shoal, a hotly disputed submerged reef in the South China Sea's Spratly Islands.

Why It Matters

The Spratlys are contested by the Philippines, China , Vietnam, Taiwan, Malaysia and Brunei. Beijing claims most of the South China Sea, including features such as Second Thomas Shoal that lie within the Philippines' exclusive economic zone.

Manila stations a small detachment aboard a rusting warship, the BRP Sierra Madre , which it grounded on Second Thomas Shoal in 1999 to reinforce its claim to the reef—a move China maintains was illegal.

Since 2023, Philippine resupply missions to Second Thomas Shoal have faced forceful Chinese actions, including collisions and water-can

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