A Chinese warship confronted an Indian navy vessel shortly after it left Vietnamese waters in late July, in the first such reported encounter between the two countries navies in the South China Sea.
The unidentified Chinese warship demanded that Indias INS Airavat, an amphibious assault vessel, identify itself and explain its presence in international waters shortly after it completed a scheduled port call in Vietnam, five people familiar with the incident told the Financial Times.
This latest example of Chinas naval assertiveness has irked defence officials in India and Vietnam. China claims the South China Sea in its entirety, rejecting partial claims by Vietnam, Brunei, Malaysia, the Philippines and Taiwan over the resource-rich region.
Any navy in the world has full freedom to transit through these waters or high seas, said one Indian official familiar with the encounter. For any country to proclaim ownership or question the right to passage by any other nation is unacceptable.
Vietnams foreign ministry acknowledged that the INS Airavat visited the country from July 19-22, but said it had no information about the incident. The Chinese defence and foreign ministries declined to comment, as did the Indian government.
Chinas projection of maritime power, especially into the Indian Ocean, has heightened national security concerns in New Delhi, which has raised the incident with Beijing.
Hanoi is also upset by what it believes to be a deliberate provocation by Beijing, according to foreign diplomats, who said the implication of the naval challenge was that China believes it is entitled to police the South China Sea.
China and Vietnam have been trying to mend fences ever since Hanoi claimed in May that Chinese patrol boats had sabotaged Vietnamese oil exploration vessels. On Monday Lieutenant General Nguyen Chi Vinh, Vietnams deputy defence minister, concluded a high-profile visit to Beijing where he met General Liang Guanglie, Chinas defence minister. Both sides agreed to increase military co-operation and set up a military hotline.
An unprecedented series of anti-China protests broke out in Hanoi in June, with the clear acquiescence of Vietnams security officials. The government only recently cracked down on the demonstrations.
The Financial Times Limited 2011