A military variants of the Cessna 337, the O-2 series was built in some numbers, 501 O-2As going to the USAF for Forward Air Control duties, and some 31 O-2Bs were used in the psychological warfare role in Vietnam.

In 1934 the Imperial Japanese Navy issued specifications for a long-range flying boat, and Kawanishi appointed a design team headed by Shizuo Kikuttara. The prototype, the Kawanishi Type 97, powered by Nakajima Kikari 2 nine-cylinder radial engines, commenced flight testing on 14 July 1936. Some problems were experienced with hydrodynamics