The US Navy P-8A Poseidon jet was flying at 16,500 feet to get a view of low-lying coral reefs that have been turned into garrisons with five-storey buildings, large radar installations, power plants and runways sturdy enough to carry large military aircraft.
During the flight that was giving journalists from CNN a rare look at the islands, the crew was warned six times by the Chinese military to get out of their territory.
A voice said: “US military aircraft, this is China … leave immediately and keep out to avoid any misunderstanding.”
Each time the aircraft was challenged by the Chinese military, the US Navy crew’s response was the same.
The repsonse was: “I am a sovereign immune United States naval aircraft conducting lawful military activities beyond the national airspace of any coastal state.
“In exercising these rights as guaranteed by international law, I am operating with due regard for the rights and duties of all states.”
CNN was granted the chance to see how the Chinese government is rapidly expanding its militarisation efforts from a US reconnaissance plane when the harsh threat was issued.
The US Navy jet had flown over four key artifical islands in the Spratly chain where China has built up fortifications: Subi Reef, Fiery Cross Reef, Johnson Reef and Mischief Reef.