As territorial tensions mount in the area around the Spratly Islands, known in Vietnam as Truong Sa, Hanoi moves towards a sad anniversary. On March 14, 1988, 64 Vietnam’s naval personnel died in combat defending Johnson Reef, known in Vietnam as Gac Ma, against China’s assault. As the 35th anniversary of the Gac Ma battle approaches, Vietnam remains determined to defend its sovereignty over Truong Sa Islands. Last year, Vietnam was reported to conduct dredging and landfill work at several of its Truong Sa outposts. Washington’s Center for Strategic and International Studies (CSIS) said the work in the Spratly Islands had created roughly 420 acres (170 hectares) of new land and brought the total area Vietnam had reclaimed in the past decade to 540 acres (220 hectares). This landfill work is seen as a major move toward reinforcing Vietnam’s position in the Spratlys. Meanwhile, China claims most of the South China Sea and has established military outposts on artificial islands it has built there. China insists it has sovereignty over the Spratly Islands, known in China as the Nansha Islands, and its adjacent waters. The scale of Vietnam’s landfill work is still seen falling far short of the more than 3,200 acres of land created by China from 2013 to 2016. Brunei, Malaysia, the Philippines and Taiwan, also have overlapping claims in the sea, which is crisscrossed by vital shipping lanes and contains gas fields and rich fishing grounds. In recent weeks, the Philippines repeatedly complained it had spotted Chinese naval and militia vessels around Thi Tu, a contested Philippine-occupied island in the South China Sea. The Philippines has filed 77 complaints against China’s activities in the sea, including a claim that a Chinese coast guard ship on Feb. 6 directed a “military-grade laser” at one a Philippine coast guard ship on a supply mission. In February, President Ferdinand Marcos Jr said the Philippines “will not lose an inch” of territory as the Southeast Asian protested China’s “aggressive activities” in the sea. As Hanoi faces increased controversy over Spratly Islands, firstly Chinese claims of sovereignty over almost the entire South China Sea, the territorial issue remains a sensitive matter in Vietnam. Earlier this month, a tourist company in Danang was fined for using a map of Vietnam as a logo without Truong Sa and Hoang Sa (Paracel) islands.