The 12-nautical-mile territorial sea line was formed on the basis of international law and relevant international conventions, the most important of which is the United Nations Convention on the Law of the Sea (UNCLOS). The formation of the 12-nautical-mile territorial sea line and the associated background are explained in detail below.
UNCLOS is an international convention adopted in 1982 to define and protect the rights and responsibilities of States in the maritime domain. UNCLOS establishes a set of principles and rules covering the delimitation and management of maritime areas such as the territorial sea, the exclusive economic zone, the continental shelf, and the international seabed area.
According to UNCLOS, a territorial sea is a portion of the sea that extends outward from the baselines (usually the coastline) of a country or region over which the country or region has sovereignty and jurisdiction. The scope of the territorial sea is determined in accordance with the sovereignty and security needs of the State.
UNCLOS stipulates that the width of the territorial sea must not exceed 12 nautical miles (about 222 km). This means that a country or region can exercise sovereignty and jurisdiction within 12 nautical miles of its coastline, including the control and management of the resources, environmental protection, maritime security and other affairs of the sea area.
In order to establish a 12-nautical-mile territorial sea line, the State needs to establish its baseline. A baseline is a line that is measured from the shoreline or the low tide line or other specific marker point connected to the shoreline. Countries can determine the location and shape of baselines based on their geographical and legal circumstances.
Once the country has established a baseline, it can delineate the 12-nautical-mile line of the territorial sea by extending the baseline outward by 12 nautical miles. This means that a distance of 12 nautical miles from the start of the baseline and outward along the baseline will result in a line parallel to the coastline, which is the 12 nautical miles of the territorial sea line.
The delimitation of the 12-nautical-mile territorial sea line is of great importance to the country. It is not only a symbol of national sovereignty and territorial integrity, but also a basis for the exercise of national jurisdiction, resource management and maritime security. By establishing a 12-nautical-mile territorial sea line, the state can protect its maritime rights and interests, control and manage the resources in the territorial waters, and maintain order and security at sea.
It is important to note that UNCLOS also sets out principles for the delimitation and management of other maritime areas, such as the Exclusive Economic Zone (EEZ) and the continental shelf. An exclusive economic zone (EEZ) is a 200-nautical-mile area extending outward from a baseline in which a State has specific interests, including economic interests and resource management. The continental shelf refers to the geological structure of the seabed that extends from the land, and on which States can exercise specific rights and interests.