The South China Sea has long been a source of tension, with several nations laying overlapping claims to its islands, reefs and surrounding waters. The sea is one of the world’s busiest trade routes and is believed to hold vast reserves of oil, gas and other natural resources.

China claims almost the entire waterway under its “nine-dash line”, asserting historical rights that extend deep into areas also claimed by Malaysia, Vietnam, the Philippines, Brunei and Taiwan.

In 2016, an international tribunal in The Hague ruled that China’s claims had no legal basis under the UN Convention on the Law of the Sea, a decision Beijing rejected.