Vietnam lodged a formal protest Friday against China's deployment of surface-to-air missiles to the disputed Paracel Islands chain in the South China Sea.
Citing "serious infringements of Vietnam's sovereignty over the Paracels," Hanoi's Foreign Ministry Spokesman Le Hai Binh released a statement describing letters his department issued to China's Vietnamese embassy and United Nations Secretary General Ban Ki-moon.
China's state-run Global Times newspaper on Thursday confirmed the presence of unspecified weapons on Woody Island, part of the Paracels chain.
Vietnam is calling on the UN to condemn Beijing's move, saying it "threatens peace and stability in the region as well as security, safety and freedom of navigation and flight." The call comes a day after Vietnamese officials were criticized for not responding quickly to Beijing's revelation about the weapons.
The Chinese government claims a legitimate right to military facilities on the territory, which it views as its own. Although Woody Island is also claimed by Taiwan and Vietnam, in 1974, the then-South Vietnamese government suffered a naval loss to China in a battle over the Paracels.
China's long-standing control of the Paracels contrasts with other disputed territories in the region, such as the Spratly Islands, which lie some 740 kilometers southeast of Woody Island.
"Vietnam's reaction is not strong enough amid China's assertion and militarization within Vietnam's sovereignty," Professor Tuong Lai, a South China Sea analyst who served as an adviser to the late prime minister Vo Van Kiet, told VOA Vietnamese on Friday.
"Washington's role in the South China Sea issue is very important. The U.S. needs to bolster its military presence in the region to help maintain peace and stability," he added. "Vietnam has to rally support from ASEAN, the U.S. and the international community against Chinese aggression rather than verbal protests."
During a recent meeting with President Barack Obama on the sidelines of this week's ASEAN summit in California, Vietnam's Prime Minister Nguyen Tan Dung urged Washington to play a greater role in preventing militarization and island-building in the South China Sea, the government said Tuesday.
This report was produced in collaboration with VOA's Vietnamese Service.