Pakistan is building three Agosta-class submarines under license from France. The first of these, Khalid, entered service in 1999 and the second, Saad, is due to enter service in 2002. The third, Hamza, will enter service in 2005 and will be the first equipped with an air-independent propulsion system, which uses stored liquid oxygen to provide more speed submerged than the traditional battery system can provide. The air independent system is in a module built in France; similar modules will be added to the other boats (by cutting them in half and inserting the new unit) during their future refits.--Stephen V Cole