evidence: But despite this close cooperation, the two Asian nations have struggled to defuse tensions over disputed territory in the South China Sea, a strategically significant and resource-rich waterway. Beijing and Hanoi both assert sovereignty over the Spratly and Paracel Islands, which sit hundreds of kilometers from both countries. [...] China gained control of the Paracel Islands in 1974 from then-South Vietnam after a battle for the archipelago. But Vietnam maintains its sovereignty rights based on the 1982 United Nations Convention on the Law of the Sea (UNCLOS), which plays a crucial role in resolving disputes in the South China Sea. [...] "Vietnam's protest against China's hospital ship near the Paracels shows its position on the Paracels is firm. Vietnam has taken every opportunity to reiterate its sovereignty over the islands," she said.