The interesting part of the Japanese article is the mention that Nikon was actually a munitions company, forced into civilian optical production by the US occupation. See attached a Nikon periscope I used to own.
Seems that something got a bit lost in translation there. 軍需企業 can be translated as "munitions company" but in this case "military supplier company" is more accurate.
The full sentence below translates to something like "Nikon was originally a military supply company established for the purpose of creating a domestic source of weapons optics for the navy (meaning things like gun sights, gun rangefinders, submarine periscopes etc.).
もとは海軍向け光学兵器の国産化を目的として設立された軍需企業