The US Air Force has claimed two Chinese fighters intercepted a US plane on a training mission flying in international airspace over the East China Sea.
A spokeswoman from the US Air Force said a US aircraft had been conducting a routine training mission over the sea, obeying all standards of international law.
Two Chinese pilots intercepted the craft, and Lori Hodge - the air force spokeswoman - said in a statement the planes had been acting in an "unprofessional" manner.
She said the crew of the Boeing WC-135 Constant Phoenix - an aircraft designed to detect radiation - reported the incident because of how the Chinese pilots had manoeuvred their planes, how fast they were flying, and the proximity they came to the American craft.
China has remained suspicious of any US Air Force activity in the South China Sea, which it claims as its own airspace.