In the midst of war or natural disaster humanitarian aid can make the difference between life and death. But according to influential critics it can also exacerbate conflict, offer succour to tyrants and foster dangerous dependency. Stephen Sackur talks to Sir John Holmes who was the UN's Emergency Relief Co-ordinator during crises in Sudan, Sri Lanka and Haiti. Today the emergency response is focused on Syria, but the question remains the same; does humanitarian aid work for those who need it most?

(Image: John Holmes listens to Manila residents displaced by devastating floods in 2009, Credit: AFP/Getty Images)