Johnson starts out with a simple statement that puts events in perspective.
The justification for the massive global military involvement of the USA
during the period from 1945 to 1991 was
the Cold War against the Soviet Union. After 1991, though, when the Soviet
Union collapsed and the USA faced no credible enemy, the USA has continued
to maintain that global empire. For what?
The USA used Japan as a buffer against the Soviet Union during the Cold War,
but then insisted in keeping Japan as a sort of colony: why?
What are the benefits of continuing to think in Cold War terms when the
enemy of the Cold War has long surrendered?
This book examines the negative consequences of US involvement abroad; "negative" as it pertains to the reputation and interests of the USA around the world (Chalmers does not examine the benefits that others may have derived from such involvement). Hence we are treated to US atrocities in occupied Japan, US support for the dictators of Indonesia and South Korea, etc.
Given the author's personal experience in the Far East and that the book was written just before the 2001 terrorist attacks, it mainly focuses on US intervention in Asia, with sporadic mentions of Latin America. After the US wars in Iraq and Afghanistan, it feels a bit odd to read a book that centers the US "empire" on Eastern Asia, but that's actually where it started. Western Europe was relatively eager to embrace the US model of democracy and capitalism, but in East Asia it was really forced on people whose countries had never experienced it before. So in a sense it makes sense to focus on Asia. Johnson wrote at the time of the Asian crisis, when Japan was in the middle of a long stagnation and the other "tigers" were just recovering from an economic meltdown. Perhaps this explains why Johnson only focused on political and military effects of US occupation, and not on the fact that such occupation allowed those countries to prosper in relative peace and eventually outperform the USA itself.
Johnson occasionally slips into anti-USA propaganda (like when it takes for valid the claim that sanctions against Iraq caused the death of 500,000 civilians "due to disease, malnutrition and inadequate medical care", a theory that was easily debunked, if nothing else, by comparing Iraq with neighboring countries that had an even lower GDP per capita during that period, not to mention the population boom that Iraq experienced during those years). Ditto when he repeats the obsolete assertion that US bombing of Cambodia killed 750,000 peasants in a country of 7.5 million people). It is also a bit unfair to claim that the USA killed more people in Vietnam and Korea than the Soviet Union ever killed in Eastern Europe: the USA did not fund wars against the Soviet Union in Eastern Europe the way that the Soviet Union and Mao's China funded wars against the USA in Vietnam and Korea. It is debatable who caused the killings in Korea and Vietnam. It is also unfair to claim that the USA supported the European colonial powers in East Asia: both India and Indonesia got their independence thanks in part to pressures by the USA on Britain and Holland. He accuses the Clinton administration of arrogance and jingoism: they were pacifists compared with what came after them (George W Bush). He claims that the world is not a safer place after the USA started policing it, but doesn't offer a way to measure "safety": if one measures wars, casualties and the likes, the world is indeed a much safer place than it has ever been (just like Western Europe enjoyed the safest era since the Roman Empire after it was occupied by the USA). To his credit, Johnson's book did correctly predict that a "blowback" would be a terrorist attack inside the USA (although he didn't see it coming from the Islamic world, which the book largely ignores).
The book falters badly when Johnson tries to change tone and, instead of simply criticizing US policies in Asia, he advances his own proposals. He proposes to "cultivate North Korea", for example, something that has almost always resulted in North Korea buying time to do what it wanted to do (Johnson considers it "unlikely" that North Korea would develop a nuclear bomb, but North Korea was doing just about at the time that Johnson wrote the book). He blabbers incoherently about mainland China, first denouncing the aggressive stance of the USA against China but then basically advising the USA to do even worse: to become protectionist against China's main source of economic growth, its exports to the USA, something that would certainly trigger a trade war resulting in a much more serious animosity between the two countries.
Also, Johnson's "blowback" theory does not examine the other side of the coin: the USA is immensely popular in many of the countries where it supported dictatorships and even among its former enemies (Vietnam), at least much more popular than its rivals (yesterday the Soviet Union and today mainland China). The popularity of the USA in Eastern Europe (a former satellite of its enemy the Soviet Union) and in India is mindboggling. Even where it is not popular (like in mainland China and the Islamic world), it is actually the reference model for the majority of the young population (that is rapidly being "Americanized" by peer pressure, not by the CIA). There weren't only "costs" to the US empire: there were also benefits, and not only economic ones. The main benefit was to export an image that somehow convinced billions of people to become more similar to the USA than to its opposite.
Writing just after the Asian economic crisis of 1997, Johnson thinks that globalization has destroyed those countries, when in fact it turned out to be a mere blip on the radar, and today those economies are doing much better than the USA. He keeps referring to "major catastrophes" that befell Asian economies during the 1980s and 1990s, but time is clearly showing the opposite: they were net beneficiaries of globalization. He thinks that the 1997 crisis was due to a project by the USA to open up those economies; maybe so, but it certainly made those countries stronger, not weaker. He views globalization as simply a US strategy to perpetuating Cold War structures and taking full advantage from the victory against the Soviet Union. Maybe there was also a strong desire by the everyman and everywoman of planet Earth to be globalized.
The real cost to the USA was to raise its own competitors. Unlike previous empires that exploited their colonies and enriched themselves, the USA has managed to enrich its colonies, and those colonies (Western Europe and the Far East) and then the countries that copied those colonies (like mainland China and India) have become the main reason that the USA is getting poorer (relative to the rest of the world). Johnson gets it right when he says "The true costs to the United States should be measured in terms of crime statistics, ruined inner cities and drug addiction, as well as trade deficits".
It is easy to share Johnson's belief that there was no winner in the Cold War: the Soviet Union disintegrated and the United States may see its empire disintegrate by attrition. However, Johnson equates the two and that's a wild exaggeration. The USA is much more similar to Alexander's Macedonia, the first great globalizer. It might sink the way the overstretched Macedonian empire sank, but its influence on the world is already colossal.