Billions of dollars of trade takes place each year through the waterway, which also houses rich fishing grounds and gas fields.
In a meeting with his Chinese counterpart in November, US Defense Secretary Lloyd Austin raised the need to improve crisis communications, and also noted what he called dangerous behavior by Chinese military aircraft.
Despite tensions between the United States and China, US military officials have long sought to maintain open lines of communication with their Chinese counterparts to minimize the risk of a possible flare-up or handling of any mishaps.
Australia’s Defense Department said in June that a Chinese fighter jet had dangerously intercepted an Australian military surveillance plane in the South China Sea region in May.
Australia said the Chinese jet flew in front of the RAAF aircraft and released a “bundle of husks” containing small pieces of aluminum embedded in the Australian aircraft’s engine.
In June, the Canadian military accused Chinese warplanes of harassing its patrol planes as they monitored North Korean clearance evasions, sometimes forcing Canadian planes out of their flight paths.
Relations between China and the United States have been strained, with tensions between the world’s two largest economies rising over everything from Taiwan’s human rights record to its military activity in the South China Sea.
US House Speaker Nancy Pelosi’s visit to Taiwan in August angered China, which saw it as a US attempt to interfere in its internal affairs. China later started military exercises near the island.
The United States has no formal diplomatic relations with Taiwan, but is bound by law to provide the island with the means of its defense.