" American intelligence knew little about Iraq, and much of what it knew was wrong. The CIA didn’t begin to imagine that Saddam could be overthrown and then operate from underground, nor did it foresee the insurgency that followed, and the ripple effect of that fighting, inspiring jihadists across the Middle East and North Africa. The consequences of that ignorance have been immense. Roughly half a million people have died, including fifteen thousand American combatants and contractors, in the name of the war on terror. Estimates of the financial toll run from $3 trillion to $6 trillion; in today’s dollars, World War II cost about $4 trillion. And in Iraq, the only winners of the war have been Iran, whose military commanders gained political power and prestige in Baghdad while working with jihadists to kill American troops, and Russia, which has forged a regional alliance of convenience with the Iranians. "

― Tim Weiner , The Folly and the Glory: America, Russia, and Political Warfare 1945–2020