Last week, the Customs Department of China's Hainan Province issued five notices of live-fire drills between March 22 and 24 in the Paracel (Hoang Sa) Islands of Vietnam.
On March 16, Beijing also announced plans to turn Phu Lam, Duy Mong and Cay islands of Hoang Sa into cities and strategic logistics bases. Phu Lam (Woody) is the largest island in the archipelago.
Vietnamese Foreign Ministry spokeswoman Le Thi Thu Hang said Vietnam's representatives have met with Chinese counterparts and handed an official statement protesting those events.
"These activities have seriously violated Vietnam's sovereignty over the Hoang Sa Islands and gone against basic principles on settling maritime issues between the two countries," Hang said at a press conference Thursday.
Hang asserted that China has violated the spirit of the Declaration on the Conduct of Parties (DOC) in the South China Sea, complicated the situation in the waters and caused trouble for negotiations on the Code of Coduct between China and ASEAN. Vietnam calls the waters the East Sea.
She reiterated that Vietnam has full legal grounds and historical evidence to assert sovereignty over the Hoang Sa and Truong Sa (Spratly) archipelagoes in accordance with international law.
"Vietnam demands that China respect international laws, Vietnam's sovereignty, the mutual awareness of the countries' high-ranking leaders, that China end and not repeat similar activities that escalate tension in the area," Hang said.
China seized the Paracel Islands from South Vietnam by force in 1974, and has been illegally occupying a number of reefs in the Spratly Islands since 1988.
Last May, Vietnam also voiced opposition against China's live-fire drills in the Paracels.