The combination of huge standing armies, almost continuous wars, an ever growing economic dependence on the military-industrial complex and the making of weaponry, and ruinous military expenses as well as a vast, bloated "defense" budget, not to speak of the creation of a whole second Defense Department (known as the Department of Homeland Security) has been destroying our republican structure of governing in favor of an imperial presidency.
I had set out to explain how exactly our government came to be so hated around the world. As a CIA term of tradecraft, "blowback" does not just mean retaliation for things our government has done to, and in, foreign countries. It refers specifically to retaliation for illegal operations carried out abroad that were kept totally secret from the American public. These operations have included the clandestine overthrow of governments various administrations did not like, the training of foreign militaries in the techniques of state terrorism, the rigging of elections in foreign countries, interference with the economic viability of countries that seemed to threaten the interests of influential American corporations, as well as the torture or assassination of selected foreigners. The fact that these actions were, at least originally, secret meant that when retaliation does come -- as it did so spectacularly on September 11, 2001 -- the American public is incapable of putting the events in context. Not surprisingly, then, Americans tend to support speedy acts of revenge intended to punish the actual, or alleged, perpetrators. These moments of lashing out, of course, only prepare the ground for yet another cycle of blowback.
As a form of government, imperialism does not seek or require the consent of the governed. It is a pure form of tyranny. The American attempt to combine domestic democracy with such tyrannical control over foreigners is hopelessly contradictory and hypocritical. A country can be democratic or it can be imperialistic, but it cannot be both.
What Chalmers Johnson does not recognize or acknowledge is that 9/11 was not blowback - retaliation for illegal operations carried out abroad - but was itself an illegal operation carried out against the American people for imperial purposes.
Johnson himself explains why this is necessary -- the American people would not have given their consent to the plans of the imperialists. In order to maintain the pretense of domestic democracy, they had to be terrorized into accepting these plans. At the same time, the attacks enabled the aggrandizement of the presidency over congress and weakening of the judiciary and civil liberties. All of this furthers the imperial project.