Not defending Obama (I hate that SOB).... but Bush let his little head do his thinking. He wanted to be known as a "war President"... regardless of the lies he had to tell or the damage it did to the USA.
How many atomic bombs will it take to destroy the world? In the largest study ever done about what the consequences of a full scale nuclear war might be. They estimated that 14,000 weapons would be used. That it would cause a nuclear winter that would last 3 years before the atmosphere cleared. That 40% of the worlds population would die from direct effects of the nuclear weapons, starvation or disease. That study was done at the height of the cold war, when the US and the Soviet union had over 30,000 nuclear weapons. Today the world combined only has around 6,000 operational nuclear weapons. And we do not have the delivery capability to use all of them. However, i predict the USA would lose in a full blown nuclear war because 80% of our population are in urban areas, while as an example, 60% of China's population are in rural areas which are extremely mountainous. Russia's population is also very spread out. Expect Moscow,St Petersburg, LA,Chicago and NYC to be completely wiped out.