Vietnam’s foreign ministry released a map outlining its baseline claim in the Gulf of Tonkin, establishing a maritime border with China. The Ministry of Foreign Affairs announced the Declaration in accordance with Resolution No. 68/NQ-UBTVQH15, issued by the National Assembly Standing Committee on February 14, 2025.

On Friday, it stated that the move aimed to safeguard and enforce its sovereign rights. Baseline play a crucial role in defining territorial waters and exclusive economic zones, a sensitive issue in the South China Sea, where China, Vietnam, and other regional countries have overlapping claims.

Vietnam's establishment of the baseline in the Gulf of Tonkin is intended to uphold its rights and responsibilities under the 1982 United Nations Convention on the Law of the Sea (UNCLOS) and is in accordance with its 2012 Law of the Sea.

The ministry indicated the line on a map with 14 points extending from offshore Quang Ninh province to Quang Tri province.

According to a statement from the ministry, the baseline “creates an additional legal basis to protect and enforce Vietnam’s sovereignty, sovereign rights and jurisdiction, serving economic development, marine management, and promoting international cooperation”.

It stated that the baseline serves as the foundation for defining Vietnam’s maritime boundaries and zones in accordance with the United Nations Convention on the Law of the Sea and the 2000 Agreement on the Delimitation of the Gulf of Tonkin between Vietnam and China.

China's foreign ministry has yet to comment on the matter, despite a request from Reuters for a response.

In March of last year, China declared its baseline in the Gulf of Tonkin, prompting Vietnam to stress that international law, as well as the rights and interests of other nations, must be respected.