Super typhoon Yagi has been identified as the most powerful storm to hit the South China Sea in the past three decades, according to the National Center for Hydro-Meteorological Forecasting.
A tropical depression in the South China Sea strengthened into a storm on Sunday morning, with maximum wind speed of 74 kilometers per hour, and is expected to enter the Gulf of Tonkin Monday.
Vietnam urged China and the Philippines to show restraint following reports of a collision between their official vessels at Second Thomas Shoal, on Friday.
Vietnam values the maintenance of security and safety at the South China Sea and calls for countries to abide by international law while performing drills in the region.
China on Thursday slammed what it called "provocative" moves by the United States and its ally the Philippines in the South China Sea, as both sides held drills in the waters.
Chinese state media accused the Philippines on Monday of repeatedly infringing on China's territory in the South China Sea, spreading false information and colluding with extraterritorial forces to cause trouble.
China and the Philippines traded accusations over a collision in disputed waters of the South China Sea as Chinese vessels blocked a Philippine boat supplying forces there on Sunday, the latest in a series of maritime confrontations.
The Philippines on Sunday accused China's coast guard of installing a "floating barrier" in a disputed area of the South China Sea, saying it prevented Filipinos from entering and fishing in the area.