In exchange for granting base rights, FAPLA became the beneficiary of more sophisticated Soviet arms. After Operation Sceptic the Soviet Union transferred over five hundred million dollars' worth of military equipment to FAPLA, the bulk of it apparently concentrated on air defence. This made South African raids costlier in terms of the need to provide heavier air cover and likely casualties. With the adoption of more advanced weaponry, the contribution by Soviet technical and advisory support to FAPLA's operational capabilities also became increasingly crucial. Totalling between 1,600 and 1,850 advisers by 1981, the Soviet military mission to Angola was deployed within all branches of the Angolan armed forces.