The US State Department has approved the sale of two land-based Aegis weapons systems to Japan in a deal worth US$2.15 billion.
The sale also includes two Multi-Mission Signal Processors, two Command and Control Processor Refreshes, radio navigation equipment, naval ordnance, two Identification Friend or Foe systems, Global Command and Control System-Maritime hardware, two Inertial Navigation systems, technical, engineering and logistics support services, installation support material, training, construction services for six vertical launch system launcher module enclosures, and communications equipment and associated spares.
The sale is still subject to congressional approval.
In a statement, the Defense Security Cooperation Agency said that the system will allow Japan to shore up its missile defence capability.
"This proposed sale will contribute to the foreign policy and national security of the US by improving the security of a major ally that is a force for political stability and economic progress in the Asia-Pacific region. It is vital to US national interests to assist Japan in developing and maintaining a strong and effective self-defence capability.
"This proposed sale will provide the Government of Japan with an enhanced capability against increasingly sophisticated ballistic missile threats and create an expanded, layered defense of its homeland.
"Japan, which already has the AEGIS in its inventory, will have no difficulty absorbing this system into its armed forces."
In July 2018, Tokyo selected a version of Lockheed Martin's Long Range Discrimination Radar as its radar choice for the Aegis Ashore batteries.
Japan is seeking to bolster its defences against North Korean missiles.