Were we wrong? I have lived through two global conflicts: the west against Russian communism and now the west against political Islam. The latter was caused by western leaders exaggerating a threat from a tiny group of terrorists to win popularity in war. But the former? Surely the cold war was a good war, a Manichean struggle between competing visions of how to order humanity. If not, then it must have been one of the great mistakes of all time, and a horrific waste of resources.

Andrew Alexander gazes down from his Daily Mail column like a stern and scholarly heron. No one could possibly call him leftwing, let alone a pacifist appeaser. He has no illusions about the evil of Stalin or Mao, any more than he has about Saddam and al-Qaida. But he combines cussedness towards conventional wisdom with historical scepticism. In a sensational but little-noticed book, America and the Imperialism of Ignorance, he marches to the conclusion that most recent foreign policy has been based on systematic ignorance. We were duped – and still are.

Alexander agrees with the now accepted thesis that after the second world war, Stalin and his successors never meant to invade western Europe and overthrow American capitalism. As the historian Sir Michael Howard has written, "No serious historian any longer argues that Stalin ever had any intention of moving his forces outside the area he occupied in eastern Europe".

Stalin's obsession, understandably, was with stopping any German renascence. He was a brutal psychopath, but, like most Russians, his fear was of encirclement. He sought buffer states and an iron curtain to guard his borders. His stance towards the west was not aggressive. He had neither the will nor the means to wider world dominance (while the US had both).

The conventional answer to this was that Nato could never be sure. Rearmament, including nuclear weapons, was a sensible precaution: hope for the best, prepare for the worse. This also suited the macho tradition in US politics. Franklin D Roosevelt was succeeded by the hawkish Truman, who would not listen to Churchill's counselling of peace with Russia. Likewise in 1953, on Stalin's death, the US rebuffed Georgy Malenkov's desire for reconciliation. The arrogant secretary of state, John Foster Dulles, goaded the Soviets into a nuclear arms race, bringing the west close to war with Nikita Khrushchev and even during Ronald Reagan's madcap brinkmanship. Only Mikhail Gorbachev's courage and intelligence averted what might have been disaster.

Although it is easy, in any arms race, to declare a plague on both houses, Alexander is in no doubt – the fault lay primarily in Washington. A succession of bombastic American leaders, chary even of travelling abroad, denied what their own intelligence was telling them, that Russia posed no threat to the west. This is backed by recent research into Russian archives. (Alexander might have credited others who said so at the time, from CND to Enoch Powell.)

The US duly kept on being a wartime military establishment of great political power, sustained in public by a hysterical McCarthyism and evoking an equally paranoid response from the Soviet Union. This in turn bolstered America's psychological need for a titanic foe to bind the western alliance together. If no foe existed, then one had to be created. This was intriguingly paralleled by the anti-mafia Kefauver committee, which was reduced to pleading with a series of two-bit gangsters that they were surely in thrall to a satanic nationwide boss, to no effect.

The cold war consumed trillions of dollars. Hundreds of thousands died in surrogate wars around the globe. The opportunity cost in poverty and disease, in growth foregone and democracy postponed, was awesome. The embattlement of eastern Europe, like that of today's Islamist states, retarded its passage into economic and political maturity. The cold war was not a war of good against evil. It was ignorance so pernicious as to question "the integrity and basic intelligence" of those democratic institutions persuaded that they were under existential threat.

Where Alexander goes for broke is in showing how this ignorance is ongoing. With the end of the cold war – and the west's later inept handling of Russia – the west's craving for a necessary enemy has revived. For a decade after 1990, defence chiefs resorted to genocidal autocrats, drug lords and Balkan separatists to maintain their budgets, which duly dwindled. Then came 9/11 and a "clash of civilisations". Bush and Blair won elections. Bankers lent money to generals, and the military-industrial complex refloated on an ocean of myth and mendacity.

The brainwashing was ubiquitous. No book, no argument, no evidence could dissuade any British cabinet from the belief that only a giant defensive armoury stood between it and a communist takeover, and now stands against an Islamist Armageddon. Hence the need to keep nuclear-armed submarines at sea, somehow to deter an unnamed "terrorist state". Likewise, five of the original six Republican candidates for US president recently called for war with Iran for "posing a threat to the American people". What threat?

I believe Alexander is right to seek explanation not in the realpolitik of international relations, but in the motives of democratic leaders. America's belief in itself as the "greatest superpower the world has ever seen" led Lyndon B Johnson to impotent fury at being thrashed by "a raggedy-ass little country" – Vietnam. It led Washington lobbyists to protect defence spending, as Truman was advised, by "scaring the hell out of the American people". Today, a similar self-delusion leads Washington and London to claim the right to drop bombs on anyone they find "unacceptable".

To this there is only one answer. Let no day pass without headbutting an ignorant politician, and kissing a sceptical historian.

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