WASHINGTON - The United States vowed on Thursday to keep up air and sea patrols in international waters after the Chinese navy repeatedly warned a US surveillance plane to leave the airspace over artificial islands China is creating in the disputed South China Sea.
The Chinese navy issued eight warnings to the crew of a US P8-A Poseidon, the US military's most advanced surveillance aircraft, when it conducted the overflights on Wednesday, according to CNN, which was aboard the US aircraft.
When the American pilots responded by saying the plane was flying through international airspace, a Chinese radio operator said with exasperation: "This is the Chinese navy ... You go!"
The Poseidon flew as low as 15,000 feet (4,500 meters), CNN said, and video provided by the Pentagon appeared to have been taken from directly above one artificial island.
The incident, along with recent Chinese warnings to Philippine military aircraft to leave areas around the Spratly archipelago in the South China Sea, suggested Beijing is trying to enforce a military exclusion zone above its new islands there.
Some security experts worry about the risk of confrontation, especially after a US official said last week that the Pentagon was considering sending military aircraft and ships to assert freedom of navigation around the Chinese-made islands.
The senior US diplomat for the East Asia, Assistant Secretary of State Daniel Russel, told a media briefing in Washington the US reconnaissance flight was "entirely appropriate" and that US naval forces and military aircraft would "continue to fully exercise" the right to operate in international waters and airspace.
He said the United States would go further to preserve the ability of all countries to move in international waters and airspace.
"Nobody in their right mind is going to try to stop the US Navy from operating - that would not be a good bet," he said.
"But it's not enough that a US military plane can overfly international waters, even if there is challenge or hailing query ... We believe that every country and all civilian actors should have unfettered access to international waters and international airspace."
A spokesman for China's Foreign Ministry said he was not aware of the incident.
"China has the right to engage in monitoring in the relevant airspace and waters to protect the country's sovereignty and prevent accidents at sea," ministry spokesman Hong Lei said in a regular briefing. "We hope the relevant country can earnestly respect China's sovereignty in the South China Sea."