Thirty years ago, I flew into Santiago at dawn, just a few days after the coup that overthrew Salvador Allende on 11 September 1973. This was the first flight that the military allowed into the capital. John Humphrys and Michael Brunson of the BBC and ITN, with considerable enterprise and larger budgets than mine, had hired a jet airliner from Aerolineas Argentinas to accommodate their television equipment and cameramen. The large pack of journalists assembled at the airport in Argentina had expected a post-coup civil war, but they found on arrival at Santiago that they were covering a counter-revolution, something much less visually exciting. Most of them left a week or two later to cover a real war in the Middle East.

The socialist government of Salvador Allende ended both with a bang and whimper. The bang occurred on the first day of the coup, when the Hawker Hunters of the Chilean air force attacked the presidential palace, and provoked the president's suicide. The whimper lasted longer. It came from workers and their families, cowering in shanty towns, waiting for the next military raid; from thousands of people caged on the terraces of the national stadium, not certain what would happen to them; and from hundreds of government cadres melting into foreign embassies, little knowing that they faced untold years of distant exile.

This was the humiliating conclusion to a bold experiment that had caught the imagination of the world, putting Latin America on the map for the first time since the Cuban revolution. Chile was supposed to be different. Allende had always promised "the peaceful road" to socialism. So it was, but it proved to be the prelude to fascism. Chile has never quite recovered from the terrible experience of the Pinochet years. The United States bore a heavy responsibility for what took place, and in a new volume, The Pinochet File, based on recently declassified documents, Peter Kornbluh provides more detail about US involvement than anyone has yet seen.

I reported on Allende's Chile for the Guardian and the New Statesman. I had worked at the University of Chile in the 1960s, when the local Christian Democrats were presiding over what they called a "revolution in liberty". Any kind of mild reformist had to call themselves a revolutionary in those days, and Chile's Christian Democrats were so progressive that Allende took over much of their legislation. His land reform was theirs (he even inherited their minister) while his nationalisation of the US-owned copper mines, which so irritated Richard Nixon and Henry Kissinger, was supported by all Chile's political parties across the spectrum.

I thought I knew Chile well, I had friends and acquaintances on the left and the right. Yet nothing had prepared me for the metamorphosis that the country went through in September 1973. People were absolutely silent, as though they had been struck dumb, cowed as much by a sense of failure as by the prevailing atmosphere of fear and repression. I travelled up and down the country, to find that there was in fact no resistance to speak of, certainly no civil war. Most people were exhausted by the previous three years of daily political struggle, and simply surrendered to the new regime. The first crimes of Pinochet's terror squads were committed against those who had given themselves up voluntarily. For more than a decade, they ruled Chile as though it was an occupied country.

The Christian Democrat opposition had hoped to be the political beneficiaries of the coup, and I shall always remember the smug expression in those days of Patricio Aylwin Azocar, their unctuous leader. He looked as though he had won the lottery, before the smile was wiped from his face by the realisation that Pinochet disliked his party just as much as the Socialists and the Communists. All political parties were outlawed, apart from the fascist right. Christian Democrats were killed like the rest, even those in exile.

At the time, I did not share the automatic leftist belief that the United States had engineered the coup. I knew that Latin America's ruling elite of white settlers had had centuries of experience in crushing native rebellions and slave revolts, and that they hardly needed tuition from the CIA. Chile is a deeply racist country - "We have no Indians," Pinochet told Kissinger in 1976, proudly and incorrectly - and Allende's principal crime in the eyes of the white elite was to have mobilised the dark-haired mestizo majority for the first time in history. In this context, the Chilean military simply played their traditional role of keeping the natives in their place.

Yet over the years - starting even in the Allende period with Jack Anderson's revelations of the joint ITT Corporation/ CIA operations concerning the assassination of the Chilean commander-in-chief - the evidence has accumulated of the predominant role played by the US government in ensuring the overthrow of the democratically elected Chilean regime. Successive US congressional hearings have produced a stream of evidence about the activities of the CIA and other US-dominated institutions, although the actual September coup - as I had always suspected - still appears to have been home-grown.

One of the most energetic researchers, in the archives and in the welter of declassified documents, has been Peter Kornbluh of the Institute for Policy Studies in Washington - a radical think-tank permanently mobilised by the assassination, in 1976, of two of the institute's members, Ronni Moffitt and Orlando Letelier, once one of Allende's senior ministers. Kornbluh has ploughed through the rich haul of US documents released by the Clinton administration in the wake of Jack Straw's surprising arrest of Pinochet in London in October 1998. His book concentrates less on the familiar Allende period and more on the first years of the Pinochet era, when the US gave solid support to the monster they had helped to create.

In the early 1970s, Nixon and Kissinger had encouraged the Chilean military to rebel, poured millions of dollars into the Christian Democrat opposition and the rightist newspaper El Mercurio, and famously "made the economy scream". That much is common knowledge, and there is little point in wasting much breath on indignation. That is the way that the United States has always behaved in Latin America, a permanent strategy of subversion - now more accurately called "international terrorism" - that it had already been extending to much of the rest of the globe. It is now even more firmly in place in the aftermath of the cold war.

What is new in this absorbing volume is the material relating to the later 1970s, when Pinochet and his fellow dictators in the southern cone of Latin America were engaged in some international terrorism of their own. The details of their own particular conspiracy, called "Operation Condor", was already well-known to the US government when Orlando Letelier was blown up in Washington, in what Kornbluh describes as "the most brazen act of international terrorism ever committed in the capital of the United States" - before American Airlines Flight 77 was flown into the Pentagon on 11 September 2001. The Americans had no objections to death squads that killed off leftist activists and political leaders when these terrorist operations occurred in distant Latin American cities. An assassination in Washington was another matter, yet even then, it took a long time before the United States began to distance itself from General Pinochet, let alone to consider an apology for what they had been doing. Manuel Contreras, Pinochet's secret policeman, had once been on the CIA's payroll.

Next year will mark the 50th anniversary of the CIA's coup in Guatemala. This early example of US terrorism destroyed the country but at least served to warn Che Guevara (who was there at the time) and Cuba's leader, Fidel Castro, of what they could expect from the United States when they sought to take an independent road. Cuba took suitably defensive measures, and survived. Allende, curiously, was absurdly optimistic and even seemed surprised that the Americans did not play by the rules. He paid a high price for underestimating the enemy.

Kornbluh has the same kind of outraged naivety as Allende. He suggests that Chile, like Vietnam, represented "the corruption of American values". He longs for US foreign policy to return to "the moral precepts of American society". Yet just what are these "values" and "moral precepts" that once guided US governments? For the case of Chile is not some kind of exception to the way America usually behaves, especially in Latin America. It is the rule. To the detriment of the impact of his splendid investigations, Kornbluh has become just another human rights evangelist, using the Pinochet case to argue in favour of "the concept of universal jurisdiction", that current panacea which seeks to ensure that "tyrants will no longer be able to leave their homelands and feel secure from the reach of international law".

His kind of ahistorical argument makes me feel quite sympathetic (albeit very briefly) to that archetypal American terrorist Henry Kissinger who, when interviewed in 2001 and taxed with why he had not told Pinochet to stop "violating human rights", replied that "human rights were not an international issue at the time, the way they have become since".

Kissinger is strictly correct. Thirty years ago, no one called for Pinochet to be brought to justice. No one called for international intervention. They just asked that foreign leaders like Kissinger (and later Margaret Thatcher) should isolate his regime and cease to fawn over him, and allow his own people to decide what should be done with him. In Chile, and also in Uruguay and Argentina, the people have come up with different answers, which have varied over time. Yet maybe the interests of justice have been better served that way than by whisking a Pinochet or a Milosevic away to some foreign, "international" court. Meanwhile, the real international terrorists escape scot-free, time and time again.

Richard Gott's History of Cuba will be published next year by Yale University Press