Relations between China and Vietnam have undergone a subtle change following a series of provocative activities by Hanoi intended to disturb the normal drilling operations of a Chinese oil rig in the waters off China's Xisha Islands, also known as the Paracel Islands.

When the oil rig, or Haiyang Shiyou 981, owned by China National Offshore Oil Corporation, commenced operating in early May, the China Maritime Safety Administration issued a notice, demanding vessels avoid passing within a three-mile radius around the drilling site to ensure safety. In disregard of this notice, the Vietnamese authorities dispatched a large number of vessels, including armed ones, close to the site, and they have rammed China's civilian ships and disturbed the normal operations of the Chinese drilling platform.

The Vietnamese authorities also filed a protest, accusing the drilling operation of falling within "disputable waters" and violating the United Nations Convention on the Law of the Sea and the Declaration on the Conduct of Parties in the South China Sea. Hanoi has made use of the so-called "collision incident" in the South China Sea incited by the media, to describe itself a victim bullied by China.

The Chinese oil rig is operating 17 miles away from Zhongjian Island, which belongs to China's Xisha Islands, this is 150 miles away from Vietnam's coastline. It is self-evident that the site falls into China's offshore waters and that the drilling operations are completely within the range of the country's sovereignty, sovereign rights and jurisdiction and have nothing to do with Vietnam.

The Xisha Islands are a part of China's inherent territory and the drilling of the Chinese enterprise in its offshore waters is an internal affair that should be free from any outside interference. The normal and legitimate drilling operations in waters under China's jurisdiction is in compliance with the UN Convention on the Law of the Sea and anything but a violation of the Declaration on the Conduct of Parties in the South China Sea as claimed by Vietnam. Facts prove that it is Vietnam, not China, who instigated the recent tensions in the South China Sea.

In the face of provocative activities from Vietnam, China has had to reinforce security precautions on the site to ensure the safety of those on the oil rig and the safety of operating equipment. To maintain China's normal maritime operations and ensure the safety of its operating vessels, equipment, personnel and navigation, it is justified for Chinese vessels to fend off bumping Vietnamese vessels.

China has maintained the utmost restraint in the face of Vietnamese provocations to avoid the tense situation escalating. In response to the provocations, China has only used civilian vessels and chosen a diplomatic channel for communication with the Vietnamese, asking Hanoi to respect China's legitimate rights and interests and immediately stop its provocative activities.

However, such restraint has failed to gain respect. Instead, Vietnam has responded by increasing its vessels at the scene and has even mobilized some armed ships and frogmen. They have even put up a lot of fishing nets and barricades in the relevant waters, not only seriously threatening the safety of China's vessels, drilling equipment and personnel, but also seriously endangering normal navigation safety.

These provocative activities have not only seriously infringed upon China's sovereignty, sovereign rights and right of jurisdiction, they will also probably cause serious damage to the Sino-Vietnamese relations that were otherwise on the track of enhancing strategic mutual trust and deepening mutually beneficial cooperation.

In June 2013, Vietnamese President Truong Tan Sang paid a visit to China and held talks with Chinese President Xi Jinping. Both leaders unanimously agreed that friendship between China and Vietnam is the common wealth of both peoples, and both countries should continue adhering to the principles of "good-neighborliness, friendship and all-round cooperation" and continue to be "good neighbors, good friends, good comrades and good partners" to each other.

With the joint efforts of both leaders, China and Vietnam have laid out an overall pattern of coordinatively advancing maritime, land and financial cooperation, ushering in a new future of booming development in their bilateral ties. The working group for joint maritime development established by two countries has held two rounds of consultations and achieved some positive progress.

In this context, both countries should join hands to cherish and carry forward the hard-won good momentum and, in particular, remain vigilant against any alienation instigated by the United States and Japan based on their strategic interests.

There is no doubt that Vietnam's latest provocative activities in the South China Sea have had an unfavorable influence on its otherwise good interaction with China. In order to maintain the healthy development of bilateral relations and the stability of the South China Sea, the Vietnamese authorities should return to reason as soon as possible, immediately stop all provocative activities and withdraw all of its vessels and personnel from the operating site of the Chinese oil rig.

The author is a researcher with the China Institute of International Studies.