"Type 97 57 mm tank gun," Chi-Ha's primary armament was upgraded to a 47 mm tank gun with improved armour-piercing capabilities. With this improved tank, the Japanese army now had a way to combat the Americans' M3 Stuart light tank. However, when the M4 Sherman medium tank (referred to as a heavy tank by the Japanese forces) made its debut on the front lines, the Japanese army's tanks became viewed as "Tin Coffins," and remained so until the end of the war.