In an exclusive NDTV conversation, former CIA Director and US Army General David Petraeus reflects on the toughest decision of his military career: changing the US strategy during the Iraq War surge. He explains why the most important surge was not of troops, but of ideas, shifting from clearing and leaving areas to holding territory, protecting civilians and promoting reconciliation. Petraeus also discusses how warfare is changing, arguing that drones and emerging technologies are challenging the future role of tanks, manned warships and non-stealth aircraft.