The 5.56×45mm round ( SS109), first used in the M16 rifle, eventually became the standard of ammunition type for all NATO member assault rifles. However, over time, especially during the Vietnam War, the battle rifle's shortcomings became apparent, and ultimately, battles rifles began to be replaced with assault rifles, which fired intermediate cartridges, though they had a weaker effective range compared to battle rifles.
Like most other nations, Japan began the Cold War with a battle rifle – the 7.62×51mm NATO Howa Type 64. Limited numbers of the Type 89's replacement, the Howa Type 20, were purchased in 2020. It has remained Japan's principal service rifle since then. The Type 89 was introduced to replace the Howa Type 64 battle rifle in frontline units, entering service in 1989. It has never been exported outside Japan due to its strict anti-hardware export policy. The Howa Type 89 Assault Rifle ( 89式小銃, hachi-kyū-shiki-shōjū), referred to as the Type 89 5.56mm Rifle ( 89式5.56mm小銃, hachi-kyū-shiki-go-ten-go-roku-miri-shōjū), is a Japanese assault rifle used by the Japan Self-Defense Forces, the Japan Coast Guard's Special Security Team units, and the Special Assault Team.
Iron sights optical sights can be placed with Weaver or Picatinny railing mount Defense Agency Technical Research and Development Instituteĩ16 mm (36.1 in), (670 mm (26.4 in) with Howa Type 89-F)