Japanese Prime Minister Fumio Kishida and US President Joe Biden are expected to agree on the plan during their bilateral talks at the Camp David retreat near Washington on Friday, according to Kyodo News.
It will be the two nations' second joint development of an interceptor missile following the Standard Missile-3 Block 2A, the successor to SM-3 Block 1A developed solely by the United States.
Japan and the United States are aiming to beef up their alliance's deterrence capabilities in response to Pyongyang's repeated ballistic missile tests and rapid advance of its missile technologies.
Hypersonic missiles, which travel at a top speed of over Mach 5, five times the speed of sound, are hard to shoot down and track by radar.
The new missiles will be designed to bring down hypersonic projectiles before their landing phase. Some types of hypersonic missiles are capable of flying on irregular trajectories just before landing to fend off interceptors, the sources said.
Japan had originally planned to address the threat of hypersonic weapons by improving its Ground Self-Defense Force's Type-03 medium-range, surface-to-air guided missiles, which mainly target incoming aircraft, and by using the Maritime Self-Defense Force's Standard Missile-6 interceptors.
But as these SDF interceptors are intended to hit enemy weapons in the landing phase, Japan needs to acquire the ability to shoot them down while they are gliding, according to the sources.
The United States has already started the development of Aegis destroyer-fired interceptors to hit hypersonic weapons in the gliding phase, and this may be linked with the envisaged bilateral project, the sources said.
At a meeting in Tokyo in June, Defense Minister Yasukazu Hamada and his American counterpart Lloyd Austin pledged to deepen cooperation on the joint development of an interceptor to use against hypersonic technology.
On Friday, Kishida and Biden are also set to hold a trilateral summit with South Korean President Yoon Suk Yeol at Camp David.
SKH/PR
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