Pakistan's first nuclear tests were made in May 1998, when six warheads were tested under codename Chagai-I and Chagai-II. It is reported that the yields from these tests were 12 kt, 30 to 36 kt and four low-yield (below 1 kt) tests. From these tests Pakistan can be estimated to have developed operational warheads of 20 to 25 kt and 150 kt in the shape of low weight compact designs and may have 300–500 kt large-size warheads. The low-yield weapons are probably in nuclear bombs carried on fighter-bombers such as the Dassault Mirage III and fitted to Pakistan's short-range ballistic missiles, while the higher-yield warheads are probably fitted to the Shaheen series and Ghauri series ballistic missiles.