Tensions escalated in the South China Sea region this week after China , Vietnam and the Philippines were involved in a series of potentially explosive confrontations over disputed territory . Vietnamese officials say Chinese military and civilian ships have been intimidating their vessels near the Paracel Islands -- which are controlled by Beijing but claimed by Hanoi -- since Sunday , even accusing the Chinese of repeatedly ramming into them and shooting water cannons . But China blames Vietnam for forcefully disrupting drilling activities , and demand that it withdraw all vessels from the area , said Yi Xianliang , Deputy Director-General of the Department of Boundary and Ocean Affairs in a press briefing yesterday . Meanwhile , a Chinese fishing boat and its 11 crew members were apprehended on Tuesday by Philippine authorities near the Spratly Islands , another disputed region in the South China Sea . Philippine officials say the boat was carrying a large number of endangered species and they seized the boat `` to uphold Philippine sovereign rights '' in the disputed waters . `` It 's possible that an armed clash could occur , but not a full-fledged war . The situation with Vietnam is serious -- more serious than the situation with the Philippines , '' said M. Taylor Fravel , Associate Professor of Political Science at the Massachusetts Institute of Technology ( MIT ) . `` China has controlled the northern half of the Paracel Islands since the 1950s and the southern half since 1974 . Unlike the Spratly Islands , China maintains that no dispute exists over the Paracels . So we can see that China believes that its claim there is quite strong , '' he added . Exclusion zone . Relations between China and Vietnam soured on Friday , when a Chinese platform began drilling for oil near the Paracel Islands . The oil rig , Haiyang Shiyou 981 , is owned by state gas and oil company CNOOC . The Maritime Safety Administration of China ( MSAC ) declared a three-miles exclusion zone around the rig , while military vessels have been deployed to patrol the area . `` At present , the number of escorting ships of China has reached 60 , including military ships , '' Tran Duy Hai , Vice Chair of Vietnam 's National Boundary Commission , said in a statement Wednesday . `` These vessels have intentionally hit and collided with Vietnamese law enforcement ships , including those of the Maritime Police and Fisheries Control , causing damage in human and property . '' ( sic ) China maintains that its current drilling activities are legitimate and blame the Vietnamese for provoking conflict . `` The drilling activities of this rig are within China 's territorial waters . The harassment by the Vietnamese side is in violation of China 's sovereign rights , '' said Hua Chunying , spokesperson of China 's Ministry of Foreign Affairs . She did not confirm the boat collisions . According to CNOOC , a third of China 's oil and gas resources are under the South China Sea , most of which it claims as its own , refuting rival claims from Vietnam , the Philippines , Taiwan , Malaysia , and Brunei . 'Undermines peace ' In Washington , U.S. State Department Spokesperson Jen Psaki condemned China 's drilling near the Paracels . `` This unilateral action appears to be part of a broader pattern of Chinese behavior to advance its claims over disputed territory in a manner that undermines peace and stability in the region , '' said Psaki . China 's Hua hit back saying that Chinese drilling activities `` have nothing to do with Vietnam , let alone the U.S. '' Meanwhile , the Philippines Department of Foreign Affairs said it will deal with the detained fishermen `` in a just , humane and expeditious manner . '' Philippines police claimed the fishing boat was loaded with 350 endangered turtles when it was seized near an area it controls called Half Moon Shoal . China urged Manila to `` stop taking further provocative actions . '' `` It is possible that the Philippines may have been emboldened by the recent defense agreement reached with the United States . China and the Philippines are jostling for control of the waters in the area where the arrest occurred , '' said MIT 's Fravel . The arrests follow U.S. President Barack Obama 's visit to the Philippines earlier this week , kicking off the annual military drills held jointly by U.S. and Filipino forces . During the trip , the U.S. and Philippines signed the Enhanced Defense Cooperation Agreement , a 10-year security pact that gives the U.S. more military access in the region . U.S. : China claim of air rights over disputed islands 'creates risk of incident ' South Korea expands air defense zone in reaction to China .
Philippines has started drilling for oil in a part of the Spratly Islands also claimed by Vietnam . China says Chinese ships have made violent attacks on Vietnamese vessels . Vietnamese fishermen arrested by China authorities in a separate dispute . Situation could escalate into armed conflict , analyst says .