Philippine coastguard vessels are defying China by continuing to resupply troops stationed on the Second Thomas Shoal, a disputed shoal in the South China Sea. The resupply missions have become more frequent in recent months, as China has pressed its claim to ownership over almost the entire South China Sea.

On October 6, 2023, a Reuters journalist witnessed one of these tense encounters between Philippine and Chinese vessels. A Chinese coastguard ship cut off the path of a Philippine coastguard boat, coming within a meter of collision. The Philippine captain shut off the engine and activated the reverse throttle, while the Chinese coastguard issued a warning to leave.

The Philippine coastguard ship was escorting smaller boats to the Second Thomas Shoal that carried supplies for a handful of troops stationed on a makeshift garrison aboard the Sierra Madre, a World War Two navy ship that was intentionally grounded on the reef a quarter of a century ago.

The constant presence of Philippine troops on the Second Thomas Shoal has irked China and turned it into a strategic battleground. China has deployed its more modern coastguard ships and clusters of fishing boats as far as 620 miles (1,150 km) from the Chinese coast to assert its control over the area.

On this particular occasion, a grey Chinese navy ship also started to follow the Philippine coastguard boat, joining the four Chinese coastguard vessels and five other boats suspected by the Philippines of being militia. The Philippine coastguard ship hung back as the supply boats advanced to complete the remaining nine miles (17 km) to reach the troops aboard the Sierra Madre.

China condemned the resupply mission, saying Philippine vessels had “intruded” in its waters in the Spratly Islands without its permission. It has previously ordered the Philippines to tow the grounded ship away from the atoll.

The stakes are high if this brinkmanship turns to miscalculation in the South China Sea. Relations between the Philippines and China have further soured this year at a time of strengthened military engagement between Manila and Washington that Beijing says risks stoking regional tensions.

The Philippines and the United States have a Mutual Defense Treaty, and the Pentagon in May made clear it would protect the Philippines if its coastguard came under attack “anywhere in the South China Sea.”

Jay Tarriela of the Philippine coastguard said it was his country’s right to operate freely in its exclusive economic zone (EEZ) and accused China of violating international law.

“They have carried out dangerous maneuvers and blocking operations to prevent our routine operations in providing supplies for our military troops,” he told reporters.

The resupply mission to the Second Thomas Shoal is a symbolic act of defiance by the Philippines against China’s aggressive claims in the South China Sea. It is also a reminder of the high stakes involved in this maritime dispute, which has the potential to trigger a wider conflict in the region.