WASHINGTON - The United States has offered to sell 56 advanced medium-range air-to-air missiles to Japan for an estimated US$113 million (S$154 million), the State Department said on Wednesday (Oct 4).

The proposal was in response to Japan's request to buy the AIM-120C-7 missiles, developed by Raytheon Missile Systems.

Also to be included in the sale are weapon support and support equipment, spare and repair parts, as well as technical and logistical support services.

The announcement came as the US and Japan face growing missile and nuclear threat from North Korea, Kyodo News reported.

The proposed package will support the foreign policy and national security of the US by meeting the security and defence needs of major ally Japan, the State Department said in a statement.

"Japan continues to be an important force for peace, political stability, and economic progress in the Asia-Pacific region," the statement said.

The proposed sale is to be approved by Congress, the law-making body of the US.

If given the green light, the sale will provide Japan the critical capability to defend itself and US personnel stationed in the country, said the statement.

"Japan will have no difficulty absorbing these additional munitions into the Japan Air Self-Defence Force," it added.

The State Department stressed that the proposed sale will not alter the basic military balance on the region.