 But by the summer of 2016, the resources of the pro-GNA MiG-25, Mirage F-1ED and MiG-23ML aircraft were seriously exhausted because of the war, leaving these aircraft almost nonoperational in pro-GNA air force, and the main combat unit of the pro-GNA Libyan air force from then on thus became the L-39ZO Albatros.Also, by the summer of 2016, pro-GNA air forces run out of both spare parts, fuel, and even money, and without being paid, most of the mercenaries and engineers that were by then serving in pro-GNA air force just left, crippling its fighting capabilities.Pilots were another problem for the pro-GNA air force — both mercenary pilots and local Libyan pilots refused on many occasions to "bomb the Libyan people", refusing to obey orders of the pro-GNA air force to bomb pro-LNA positions and leaving because of that, which severely limited their fighting capabilities.