What's the shelf life of empires? Decades, maybe centuries. All things come to an end. Recall Shelley's great poem "Ozymandias" about the Egyptian Pharaoh Ramses the Great and his seemingly invincible kingdom. Ozymandias was Greek for Ramses. "I met a traveller from an antique land, Who said-"Two vast and trunkless legs of stone Stand in the desert. And on the pedestal, these words appear "My name is Ozymandias, King of Kings; Look on my Works, ye Mighty, and despair! Nothing beside remains. Round the decay Of that colossal Wreck, boundless and bare The lone and level sands stretch far away." It is difficult to discuss imperialism because there is virtually uniform elite opinion that the U.S. is not an empire. Washington will not willingly concede its global superpower position. But remember the omnipotent British Empire? Where is it today?

Alfred McCoy is professor of history at the University of Wisconsin. He is the author of the classic The Politics of Heroin: CIA Complicity in the Global Drug Trade". For Closer than Brothers, his pioneering book on the impact of CIA torture on the Philippine military, he was awarded the Goodman Prize. He is also the author of A Question of Torture and Policing America's Empire.