The E-2D Advanced Hawkeye aircraft, made by Northrop Grumman, are equipped with powerful radars that can detect other planes and ships at long range.

Worth an estimated $3.1 billion, the deal would also include associated technology and spare engines.

Congress has 30 days to raise objections to the sale, though this is unlikely given that Japan is a close US ally.

"It is vital to US national interests to assist Japan in developing and maintaining a strong and effective self-defense capability," the State Department said.