Vietnamese President Nguyễn Phú Trọng called for China to “exercise restraint” in the South China Sea on Thursday in a virtual speech at the 75th annual U.N. General Assembly. The call for moderation follows months of Beijing’s belligerent actions in the contested maritime region.

“Together with countries within and outside the region, we are committed to the maintenance and promotion of peace, stability, maritime security and safety and freedom of navigation in the East Sea (South China Sea), in accordance with international law, particularly the 1982 United Nations Convention on the Law of the Sea [UNCLOS],” the president said.

“We call on all concerned parties to exercise restraint, avoid unilateral acts that would complicate the situation, and settle disputes and differences through peaceful means with due respect for diplomatic and legal processes,” he added.

Vietnam serves as the 2020 Chair of the Association of Southeast Asian Nations (ASEAN), a ten-member organization promoting intergovernmental cooperation in the region. Several ASEAN member states border the South China Sea, which Beijing claims to have historical rights over, almost in its entirety. In 2016, an independent arbitral tribunal established under UNCLOS ruled Beijing’s claims to nearly the entire South China Sea were illegal.

Beijing refused to accept the ruling and has continued to push forward with its illegal claims to the sea.

In recent months, China has encroached upon other nations’ sovereign territory in the sea with increasing frequency. China’s Coast Guard often bullies other nations’ fishing and exploratory fleets, preventing them from gathering natural resources within their own exclusive economic zones. For years, China has occupied other countries’ reefs and islets in the South China Sea, building them up as military outposts. It has bolstered its military presence on several of these installations recently as well.

China has targeted Vietnam, in particular, over the past six months. On April 3, China’s Coast Guard hit and sunk a Vietnamese fishing boat in waters off of Vietnam’s Paracel Islands, prompting Hanoi to issue an official diplomatic protest against Beijing. In July, China’s People’s Liberation Army (PLA) deployed eight fighter jets to Vietnam’s Woody Island.

Part of the Paracel Islands, occupied Woody Island is home to Beijing’s largest artificial military installation in the South China Sea. The PLA has previously built an airstrip and hangars on the island and equipped it with HQ-9 surface-to-air missile batteries.

Responding to China’s increased illegal activity in the South China Sea, ASEAN said on September 9 that it was working on a draft code of conduct for the maritime region consistent with international law, including UNCLOS. In a statement, the organization said it was prompted to draft the conduct code after “[c]oncerns were expressed by some Ministers on the land reclamations, activities, and serious incidents in the area, which have eroded trust and confidence, increased tensions, and may undermine peace, security, and stability in the region.”