Vietnam seized a Chinese fuel vessel after it allegedly crossed into Vietnamese waters, the worst maritime face-off between the two claimants of South China Sea assets in recent weeks amid an ongoing 'fish war' in the waters of the region.
Vietnam's coast guard captured the vessel and towed it to the northern port city of Hai Phong along with its captain and two sailors, the Thanh Nien newspaper reported.
The Chinese ship was under the disguise of a fishing boat but it carried 100,000 liters of diesel oil when it was intercepted by the coast guard near Bach Long Vi island in the Gulf of Tonkin.
The state media said the sailors admitted they were carrying fuel for Chinese fishing boats in the region.
Reports in the Vietnamese state media say more than 100 Chinese fishing ships have been chased away from Vietnam's waters in the last two weeks of March.
Vietnamese fishermen have been complaining that they face harassment from Chinese fishing vessels in the area. There have been complaints that the Chinese fishing vessels even confiscate the Vietnamese fishermen's catch.
China and Vietnam are locked in a fierce territorial dispute in the South China Sea. While China lays claim to the whole of South China Sea, Vietnam and Taiwan have claims to the Paracel island chain.
Philippines, Malaysia and Brunei are engaged in a territorial dispute with China over the ownership of the Spratly island china in the disputed waters.
China took the control over the Triton island in 1974, defeating Vietnamese forces in the Paracels. Vietnam lost more than 70 soldiers in the Chinese military offensive for the Paracels.
In 2014, China set up a drilling rig in waters near the Paracel Islands and in 2015 satellite images showed Beijing was building an airstrip on land reclaimed around the Spratlys.
More than 20 people were killed in nation-wide anti-China protests in Vietnam after China's rig move. China withdrew the rig after conducting drilling for two months.
The dispute and strategic points
The overlapping claims of sovereignty over two island chains by China, Taiwan, Malaysia, the Philippines, Vietnam and Brunei has made the South China Seas a sensitive region. The United States has strategic interests in the region as well, and it offers a counter balance against Beijing's influence in the waters.
The US adopts a stern line against China's land reclamation, construction and militarisation in these islands but China staunchly defends its claim to sovereignty in the region.
The US too has US military facilities in Southeast Asia -- Philippines and Thailand. It also has stationed its Poseidon sub-hunters and electronic warfare platforms in Malaysia and Singapore.
The mostly uninhabited islands in South China Sea are of crucial strategic importance. The two major island chains -- the Paracels and the Spratlys -- are thought to harbour natural resources around them. China hopes the oil and natural gas reserves in the region could ensure its energy security.
The sea is also a major trading route through which ship-borne trade worth $5 trillion passes every year.
For energy hungry China the sea routes in South China Sea are crucial as most of its imported oil flows through these routes.
Control over the territory allows Beijing to prevent the US from expanding its sphere of influence in the region.