The said note is not the only evidence of the Vietnamese government's recognition of the Xisha Islands being part of China's territory through diplomatic or other official channels. During a meeting with the charge d'affaires of the Chinese embassy in Vietnam on June 15, 1956, the Vietnamese deputy foreign minister explicitly expressed that" from a historical perspective and based on the documents from the Vietnamese side, the Xisha Islands should belong to China's territory".

Following the drawing of a" theater of war" by the US government, the Vietnamese government issued a statement on May 9, 1965, saying that US president Lyndon Johnson's inclusion of" the entire Vietnam, 100 nautical miles off its coasts as well as some waters of the territorial sea of China's Xisha Islands" as the "theater of war" for the US armed forces, constitutes a direct threat to the security of Vietnam and its neighboring country. The above official stance of the Vietnamese government toward China's sovereignty over the Xisha Islands was also reflected in its official maps, newspapers, journals and textbooks. As a matter of fact, the Vietnamese government never changed this stance until its south-north reunification in 1975.

According to the principle of equitable estoppel of international law, the Vietnamese government cannot overturn its previous official stance on the sovereignty of the Xisha Islands. The attempt by the Vietnamese government to reinterpret Pham Van Dong's verbal note will be futile. On the one hand, the note is not the only official evidence of Vietnam's recognition of Xisha Islands as a part of China's territory. On the other hand, according to the principle of "the land dominates the sea", the right of sovereignty over the territorial sea of a coastal state originates from its sovereignty over its land or islands. Thus, Pham Van Dong's recognition and respect to China's 12-nautical miles territorial sea inevitablely indicates its recognition and respect of China's sovereignty over the Xisha Islands.

The so-called dispute over the Xisha Islands has been completely concocted by Vietnam in the otherwise peaceful South China Sea. In recent years, the Vietnamese government has repeatedly claimed that "China occupied the Xisha Islands by force in 1974, which was an act of aggression and a violation of the UN Charter and the basic norms of international law". But China's self-defense against South Vietnam on the Xisha Islands in 1974 is not a remote episode whose truth should be known by everyone. Modern international law prohibits the unlawful use of force in resolving international disputes, but according to Article 51 of the UN Charter, a sovereign state has the right of self-defense to maintain its territorial integrity. China's self-defense against South Vietnam in 1974 came after its illegal attempt at occupation of China's Xisha Islands. The truth of this fact allows no distortion.

The Vietnamese government should not go back on its commitments on such big issues as territorial sovereignty. Otherwise, how can it build its national reputation in the international society?

It is now also time for Vietnam to account to China and the international society for its successive armed occupation of 29 islands and reefs affiliated to China's Nansha Islands since the 1970s , which is an obvious renegade of its own recognition of the Nansha Islands as a part of China's territory.

The author is an associate professor of international Law at China Foreign Affairs University.