Myanmar pro-democracy fighters, including the Mandalay People's Defence Force drone unit, continue to launch aerial assaults on military bases using drones. These attacks challenge the military's dominance of the skies and have forced the military to retreat from positions. The ethnic minority armed groups have also used drone attacks in their recent offensive. The Mandalay PDF drone unit, started by two engineering students, has more than 50 members and uses 3D printers to produce prototype 'drop bomb' shells.