The Yomiuri Shimbun reports that Tokyo has concluded that it is more cost-effective to build a new missile defense layer based on the Aegis Ashore solution rather than THAAD.
By Commander, U.S. Naval Forces Europe-Africa/U.S. 6th Fleet (Aegis Ashore Missile Defense Complex Romania) [Public domain], via Wikimedia Commons
The Ministry of Defense plans to make a decision by summer and the project will take several years to implement.
The Aegis Ashore project will need to rely on the SM-3 Block IIA interceptor in order to cover the whole of Japan with two sites.