The proposed sale will provide Japan with an increased ballistic missile defense capability to assist in defending the Japanese homeland and USA personnel stationed there.
Under the new system, even if Aegis vessels in the Sea of Japan were to use up all their missiles, it is expected that Aegis vessels stationed in the Pacific Ocean or other distant waters could shoot down a target.
"The government of Japan has requested a possible sale of four (4) Standard Missile-3 (SM-3) Block IIA missiles", the release said on Tuesday.
This arms sale comes as tension on the Korean peninsula has been slightly eased over the inter-Korean talks held on Tuesday. By comparison, the Block IIA has a range of 2,500 km, or 1,350 miles.
The new system will add to Japan's current two tiers of missile defense - Aegis destroyers equipped with Standard Missile-3 interceptors, and ground-based Patriot Advanced Capability-3 interceptors.
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The deal will improve Japan's ability to work with US missile defense systems and protect USA military bases in the region while creating USA defense jobs and supporting the health of the USA defense industrial base.
Onodera observed the computer system which sends commands to interceptor missiles. ICBMs travel higher and faster and are more hard to counteract.
The Japanese government is leaning toward the inclusion of the Integrated Air and Missile Defense (IAMD), the envisaged missile defense system laid out by the USA military, in the National Defense Program Guidelines, which is expected to be revised this year.
The MSDF now has four Aegis destroyers for the nation's missile defense.
The missile deal follows a year of ramped-up North Korean missile launches, some of them over Japanese territory, and its sixth and most powerful nuclear test.
Secretary of Defense James Mattis spoke with Japan Minister of Defense Itsunori Onodera on Monday to discuss a range of US-Japan Alliance matters and reaffirmed US commitments to the defense of Japan - pledging to work closely with his Japanese counterpart to bolster critical Alliance capabilities.