 The bulk of Armenia’s aviation-related investment, however, went to greatly strengthening the Armenian Air Defense organization.With Russian technical assistance and contributions of anti-aircraft weapons and equipment, within a year Armenia was able to integrate most of the Soviet radars and surface-to-air missiles (SAMs) left in its territory into a coherent and effective air defense system, which it officially declared operational in April 1994.Aircraft additions were few, but by the end of 1994 the Armenian Air Force’s inventory had reached an estimated 5–6 operational Su-25s (one has long been non-operational) and possibly one MiG-25 combat aircraft; two L-39 and ten Yak-52 trainers; six An-2, two An-72, one Tu-134, one Tu-154 transport aircraft; and two Mi-2, seven Mi-8/Mi-17, 15 Mi-24 helicopters.