Mozambique recently revived its air force by shipping its eight MiG-21 fighters to Rumania to be refurbished and upgraded. Some of these aircraft (six single seat fighters and two dual seat trainers) had not flown since the 1990s. Lack of maintenance, especially periodic refurbishment, is what left these aircraft grounded, baking in the tropical heat and rain for two decades. Mozambique did the math and realized it was cheaper to have Rumania refurbish the aircraft than to buy new ones. Rumania had already done this for a hundred of their own MiG-21s and successfully offered inexpensive MiG-21 refurb and upgrade services to foreign customers.
Without these MiG-21s Mozambique had no combat aircraft (other than one or two Mi-24 helicopter gunships, which are sometimes able to fly). The Mozambique air force is tiny, with about a thousand personnel and fewer than twenty aircraft, most of them grounded for lack of maintenance. This is a common situation in Africa, where corruption and a lack of local air threats leads to neglect of the air forces (except aircraft used to move key people around). Air support for the army and police would be nice but that requires a lot of cash to obtain competent pilots (ground support missions require some flying skill) and maintenance personnel. The infrequent need for ground support makes the air force seem like an unnecessary luxury especially since many African dictators have known that successful rebellions tend to begin with rebel air force pilots bombing the presidential palace and the barracks of loyal troops.
There are other reasons for Mozambique improving its air force. Government finances have improved in Mozambique as has an effort to control corruption in the military. Former colonial powers has offered inexpensive training for pilots and maintenance personnel. So by the end of the year Mozambique will have a functional air force again.