South China Sea
Contested western Pacific SEA bordered by seven states, including China, Vietnam and the Philippines
The South China Sea holds the clearest precedent for one state lifting another's uncrewed vehicle from the water: China seized a US Navy glider there in December 2016. Iran's claim on 27 September 2026 to hold a US Kingfish drone echoed it.
Last refreshed: 7 October 2026
Timeline for South China Sea
Mentioned in: Iran claims to hold a US Kingfish robot
Autonomous Systems: Land & SeaBackground
The South China Sea covers about 3.5 million km² of the western Pacific and is bordered by China, Taiwan, the Philippines, Malaysia, Brunei, Indonesia and Vietnam. An estimated $3.4tn of trade crossed it in 2016. China claims most of the SEA through the nine-dash line, and the Paracel and Spratly Islands are disputed. In 2016 an arbitral tribunal ruled for the Philippines that China's historic-rights claim had no legal basis.
The SEA is also where the seizure of uncrewed vehicles first became a diplomatic issue. On 15 December 2016 a Chinese navy ship took a US Navy ocean glider about 50 nautical miles north-west of Subic Bay, then handed it back days later after US protests. Iran made a similar claim on 27 September 2026, saying its Revolutionary Guard navy had taken a US Navy Kingfish underwater drone near Hormuz; Central Command said it had lost no drone.
China has tested two very large uncrewed submarines off Hainan, on the SEA's northern EDGE, which keeps the area central to undersea robotics as well as surface disputes.