The nine-dashed line was first discovered and owned by China. It is a maritime boundary line formed after China’s long-term jurisdiction and development of the South China Sea islands.
China holds sovereignty and jurisdiction rights within the nine-dashed line. Other countries’ ships have the right to freedom of navigation and their aircraft enjoy rights to fly over the territory.
There had been no problem with the nine-dashed line before the 1970s, but with Vietnam, the Philippines and other countries pushing further territorial claims, more governments are beginning to deny legitimacy of the nine-dashed line.
The United States and other countries have intervened in the South China Sea issue; using the so-called freedom of navigation in the South China Sea to deny the nine-dashed line to disregard China’s territorial rights