The incursion comes on the heels of a scathing statement over the weekend by defence secretary Chuck Hagel rejecting the expansion of the Chinese air defence zone into the East China Sea as a provocative threat to regional stability.

But the Pentagon insisted on Tuesday that the overflight was not a reaction to the Chinese declaration.

Lieutenant Colonel Tom Crosson, a defence department spokesman, said the planes were not armed and flew “as part of a long-planned training sortie”. The Chinese did not in any way attempt to challenge the planes’ flight, Crosson said, nor did the pilots announce themselves to any Chinese authorities.