The Trump administration has approved a $US130 million ($A182 million) missile defence sale to Japan to meet the escalating threat from North Korea.
The State Department said Congress was notified of the proposed sale of four missiles for the SM-3 Block IIA interceptor.
The system was jointly developed by Japan and the US. The missiles can be used at sea with Japan's current Aegis-equipped destroyers and with the land-based Aegis system its cabinet approved for purchase last month.
That is intended to bolster Japan's current missile defence and perhaps curry favour with President Donald Trump who is eager for US allies to buy more American military hardware.
The department says the sale will support the American defence industry and underscores Trump's commitment to improve the defence of allies threatened by North Korea.
