 Japanese focus on the distances of their Pacific trade routes encouraged development of the widest variety of submarine cruisers, including the A, B and J types.Germany decided against building projected 3,140-ton type XI U-boats with an aircraft hangar and four guns.Long-range submarines with less impressive deck guns, including Type IXD2 U-boats and United States Navy fleet submarines, evolved through the Second World War; and may be identified as cruiser submarines in comparison to submarines designed for shorter patrols over lesser distances.