Aerospace and defence company Alliant Techsystems (Atk) will deliver 20mm and 30mm tactical and training ammunition for the US Navy and Air Force, respectively, under two new contracts worth $31m.

The Minneapolis-based company will deliver 20mm mk244 armour-piercing rounds for the US Navy 20mm Phalanx anti-missile system, while 30mm PGU-15 target practice ammunition for the US Air Force’s A-10 Warthog.

The navy deliveries will begin in December 2009, while delivery of ammunition for the air force will start in 2010 under the multiple-year contract.

The fast-reaction, rapid-fire 20mm Phalanx close-in gun system provides US Navy ships with a terminal defence against anti-ship missiles.