After acquiring the Boeing 707 in the early 1970s, the Air Force was able take a large share of the transport missions that until then were made through the use of merchant ships, reducing the connection time between the different territories. The tactical missions undertaken by the Portuguese Air Force in the three theatres of war were:  The missions were carried away from a well developed network of air bases and other airfields. By the early 1970s, in the Angolan theatre there was a central air base, two sector air bases, eight satellite airfields and nine other airfields. In the Guinean theatre there was a central air base, three satellite airfields and other three airfields. In the Mozambican theatre, there was a central air base, four sector air bases, seven satellite airfields and five other airfields. Besides these, there was a high number of other air fields and runways, with almost all isolated military garrisons having their own. The air connections between the theatres and European Portugal were further supported by transit airfields in São Tomé Island, São Tomé and Príncipe and in Sal Island, Cape Verde. In Angola and Mozambique, Volunteer Air Formations (FAV, "Formações Aéreas Voluntárias") units were formed, composed of civilian volunteer pilots who assisted the Air Force in several missions, mostly transport and reconnaissance, using both civilian and military light aircraft. The Air Force also participated in ground and air-ground operations with its paratrooper forces, which became one of the main shock forces of the Portuguese Armed Forces. These troops, in the beginning of the War were mainly launched by parachute to the operations areas, but later were mainly employed in air assault operations using Alouette III and Puma helicopters. Besides the four regular paratrooper battalions (one in Angola, one in Portuguese Guinea and two in Mozambique), the Air Force was also involved in the creation of the paramilitary elite Paratrooper Special Groups in Mozambique. In order to terminate the guerrilla infiltration in the Angolan northern border, a special composite aviation/paratrooper unit - integrating trackers, paratroopers, helicopters and light aircraft - was created, this becoming the Counter Infiltration Tactical Unit ("Unidade Táctica de Contra-Infiltração"). Mainly due to the international arms embargo to Portugal, the Air Force had to struggle with a limitation of means, being obliged to extend the use of old aircraft or to employ aircraft that were not suited for the kind of warfare that was being fought.