Humanitarian aid workers belonging to United Nations organisations, PVOs / NGOs or the Red Cross / Red Crescent have traditionally enjoyed both international legal protection, and de facto immunity from attack by belligerent parties. However, attacks on humanitarian workers have occasionally occurred, and became more frequent since the 1990s and 2000s. In 2017, the Aid Worker Security Database (AWSD) documented 139 humanitarian workers killed in intentional attacks out of the estimated global population of 569,700 workers. In every year since 2013, more than 100 humanitarian workers were killed. This is attributed to a number of factors, including the increasing number of humanitarian workers deployed, the increasingly unstable environments in which they work, and the erosion of the percep