 The large turret weapon that is used to shoot down the American jet  is a Phalanx CIWS, which combines radar and computer targetting with  a 20mm armour piercing projectile to provide a short range defense  system firing approximately 75 rounds per second. In the War Room,  when the inventory of the Missouri is read out, they noted that the  ship was carrying "40,000 rounds of Sea Whizz" which is an  often