The Type 98 20 mm AA Machine Cannon was the most common light anti-aircraft gun of the Imperial Japanese Army. The Type 98 designation was given to this gun as it was accepted in the year 2598 of the Japanese calendar (1938) About 80% of IJA light AA guns were Type 98. It entered service in 1938 and first saw combat in Nomonhan. It was used until the end of World War II.