Alison Reef (; Tá»Âc Tan Reef (); Mandarin ) is a reef on the Spratly Islands in the South China Sea. The reef has been occupied by Vietnam since 1988. It is also claimed by China (PRC), the Philippines, Vietnam, and Taiwan (ROC).
In early December 2022, Vietnam began dredging and filling activities at the Tá»Âc Tan A island site. By November 2023, Tá»Âc Tan A had become an artificial island with an area of approximately 2 hectares, a length of about 150 meters, and a width of about 140 meters. Vietnam began filling and dredging at the Tá»Âc Tan C island site in September 2024, and at the Tá»Âc Tan B island site in December 2024. The three islands together total 6 hectares.