President Donald Trump’s administration has expressed concern over reports that China is interfering with oil and gas activities in the South China Sea, including Vietnam’s long-standing exploration and production activities, calling Beijing to stop its bullying actions in the region.

In a statement on Saturday, July 20, the U.S. State Department said, “China’s repeated provocative actions aimed at the offshore oil and gas development of other claimant states threaten regional energy security and undermine the free and open Indo-Pacific energy market.”

One day earlier, on July 19, Vietnam’s Ministry of Foreign Affairs accused China of violating its sovereignty, claiming a team of Chinese oil survey vessels entered Vietnamese waters.

“Over the last several days, the Chinese survey ship, Haiyang Dizhi 8, and its escorts conducted activities in the Southern area of the East Sea,” said the ministry spokesperson Le Thi Thu Hang. The South China Sea is known as the East Sea in Vietnam.

“That violated Vietnam’s Exclusive Economic Zone and Continental Shelf as established in the provisions of the 1982 United Nations Convention on Law of the Sea, to which Vietnam and China are parties. This area lies entirely within the Vietnamese waters,” Hang said.

The spokesperson added that Vietnam has delivered a diplomatic note to oppose China’s violations, and demanded Beijing to stop all unlawful activities and remove its ships from Vietnamese waters and respect the country’s sovereign rights.

South China Morning Post reported the maritime standoff emerged between the two countries after a Chinese vessel accompanied by coastguard ships entered Vanguard Bank – the westernmost reef in the Spratly Islands – to conduct seismic research from July 3. Vietnam sent its own coastguard vessels to the area in response.

Amid the confrontation, Chinese foreign ministry spokesman Geng Shuang, on Wednesday urged Vietnam to respect China’s sovereign rights and jurisdiction over the relevant waters, and not to make any move that may complicate matters.

In its statement, U.S. State Department said China’s reclamation and militarization of disputed outposts in the South China Sea, along with other efforts to assert its unlawful maritime claims in the region, including the use of maritime militia to intimidate, coerce, and threaten other nations, undermine the peace and security of the region.

“The United States firmly opposes coercion and intimidation by any claimant to assert its territorial or maritime claims,” the department spokesperson Morgan Ortagus said.

“China should cease its bullying behavior and refrain from engaging in this type of provocative and destabilizing activity” she added.

China is known for frequently trigger disputes outside its mainland territory, several weeks before the anniversary of major deplorable events, in order to mislead its people opinions. The latest provocative action in the South China Sea began three weeks before China marks the 20 years of Falun Gong persecution, which falls on July 20, 2019.