Quadcopters, electromagnetic rifles and an AI-powered navigation system were among the wares displayed at one of Africa and the Middle East’s biggest arms expos, as defence companies jostle to break into regional markets increasingly defined by drone warfare. Cheap, deadly "unmanned aerial vehicles," or UAVs, have been rapidly developed in the war in Ukraine and also transformed recent conflicts from Ethiopia and Sudan to Libya and Yemen. That has created potentially lucrative opportunities for industry behemoths and startups alike in a market in which countries are spending billions.