U.S. Navy and Marine fighter pilots, who had little high-altitude flying experience to begin with, were at a disadvantage from the start because their F4F Wildcat was slower, heavier, less maneuverable, and a poorer climber than Japanese A6M Zero. The American pilots learned quickly not to dogfight with the Zero. Instead, if they became engaged with one, they would give it a quick, diving firing-burst and then dive away to regroup, climb, and attack again. Cactus pilots had to constantly refine their tactics and techniques, rely on teamwork in dogfights and improve their gunnery to remain effective against the Zeroes.