China's Maritime Militia Was More Active Than Ever in 2025
China's militia of military-trained fishing crews spent more time deployed in the South China Sea than ever before last year, according to CSIS' Asia Maritime Transparency Initiative. In a new report based on satellite imaging, AMTI detailed the movements of identifiable maritime militia vessels near 12 reefs, and found that the sustained Chinese presence in sensitive areas of the region numbers in the hundreds of vessels - every day.
Nearly half of the activity occurred at Chinese-claimed Mischief Reef and Whitsun Reef. Mischief is occupied by China and has been built up into a massive military installation, used for staging operations throughout the Spratly Islands. Satellite images of the lagoon at Mischief Reef from September 2025 show a remarkably large presence at the anchorage, including flotillas of dozens of vessels rafted together. Four times in 2025, the accumulation of Chinese fishing vessels at this shoal alone exceeded 200 trawlers. In parallel to the buildup at this location, the number of fishing vessels at Fiery Cross Reef - another Chinese mega-base - has virtually vanished.
Whitsun Reef, just 50 nautical miles to the west of this Chinese base, is undeveloped and claimed by the Philippines; it has been the site of repeated mass gatherings of Chinese maritime militia trawlers over the years.
The deployment patterns in the western Spratlys complemented the movements of the China Coast Guard at other, more hotly-contested features. The CCG showed record activity near Scarborough Shoal in 2025, but was not accompanied by many maritime militia vessels at that location; instead, the fishing fleet focused its efforts elsewhere.
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AMTI divides the maritime militia into two categories: the "Spratly Backbone" fleet of subsidized commercial fishermen, with secondary training as militiamen; and the professional full-time militia vessels, which are fewer in number but have higher capability for paramilitary missions. According to the think tank, the shift of the Spratly Backbone vessels to Mischief Reef - away from the hottest action in the area - is effectively a demotion for the largest component of the militia.
"[The relocation] likely reflects the diminishing value of the Spratly Backbone fleet to China now that the international community knows they are not legitimate fishers, as well as the overriding focus on sustaining persistent CCG and professional militia operations around Scarborough and Sabina [Shoals]," AMTI concluded.