The report said China's illegal reclamation work in the East Sea has destroyed coral reefs, damaged fisheries in a region heavily dependent on seafood, and breached international law on environmental protection.
The scale and speed of China's activities are of particular concern given the biodiversity of the area, and the significance of the Truong Sa (Spratly) Archipelago to the regional ecology.
Between December 2013 and October 2015, China reclaimed about 12 km2 of land on 7 sites it occupies illegally in the Spratly Archipelago. China's dredgers have deposited sand and gravel on reefs, destroying the coral beneath.
Dredgers also stir up plumes of sand and silt that damage coral tissue and block sunlight from organisms, which cannot survive without it. The sand and gravel have either killed fish or expelled them from the reefs and hurt the health of fisheries in coastal areas.
The US-China Economic and Security Review Commission blamed China for having published insufficient information about its assessment of the environmental impact from artificial islands.