Fred Halliday examines assassinations that shaped the modern world, including one that empowered bin Laden

The rioting in Khartoum over the death in a helicopter crash of John Garang, veteran leader of the Sudan People's Liberation Army and only recently installed as Sudan's vice-president, highlights one of the recurrent problems of modern global politics: the belief that whatever the evidence, no death of a political figure - in a plane, car or as a result of "natural causes" - can be accidental.

Sudan's Government, newly committed to a coalition with Garang's former guerrilla opposition in the south, has promised an independent inquiry. But given the political passions and suspicions involved, few can believe this will resolve the issue.

In all of this, the Sudanese are not alone. The death of Yassir Arafat in November 2004 for reasons that are still not clear has led many in the Arab world to believe he was poisoned by the Israelis. When King Faisal of Saudi Arabia was stabbed to death by a deranged relative in 1975, the Arab world was full of conspiracy theories: "the Russians", "the Americans", everyone, it seems, was involved.

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In what was perhaps the most prominent assassination of all in the 20th century, that of President John F. Kennedy in November 1963, a vast industry of myth, plot and insinuation grew. A freephone service called "dial-a-conspiracy" produced a different version each day of a seamless web involving Kennedy, his brother Bobby, Marilyn Monroe and a cast of thousands.

Such an appetite for conspiracy serves as a background and a caution to evaluating an issue on which some recent research has cast new light: the role of political murder in the Cold War.

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The Cold War lasted more than 40 years until the collapse of East-Central European communism in 1989-91. During this period, Europe was largely at peace, but elsewhere more than 20 million people died in multiple conflicts in what was known, for most of the period, as the Third World. From Korea to Vietnam, Afghanistan to Guatemala, Angola to Nicaragua, Cambodia to Iran, the Cold War reaped a devastating harvest.

But between the comfort zone and the killing field, it also generated another form of violence: assassination, covert killing, state and judicial execution. The revelations of the past decade raise fresh questions about the extent and nature of this violence, and the legacy it leaves to a world now steeped in a new global conflict.

Modern history is replete with assassinations that have had a dramatic impact on national and international politics. The killing of Alexander II by anarchists in 1881 unleashed repression and anti-Semitism in the Russian Empire. The slaying of Archduke Franz Ferdinand of Austria in 1914 in Sarajevo sparked the Great War that drowned Europe in blood and inaugurated what historian Eric Hobsbawm calls "the short 20th century". The shooting-down in 1994 of the plane carrying Rwanda and Burundi's presidents, Juvenal Habyarimana and Cyprien Ntaryamira, precipitated the Rwandan genocide.

Such examples could be multiplied. The inception and the end of the Cold War era in Europe was marked by political deaths that had a direct relevance to the wider global stand-off between the two superpower blocs.

When the Czech liberal politician Jan Masaryk fell from the window of Prague's iern!n Palace in 1948, it marked a crucial step in the consolidation of communist rule, while the military trial and execution of Romanian dictator Nicolae Ceausescu and his wife, Elena, in 1989 symbolised the end of communist power in much of Europe.

During the Cold War period, there were other examples of political killings that had a profound impact on domestic and international politics: the murder of the Congolese nationalist leader Patrice Lumumba by soldiers, with the connivance of the Central Intelligence Agency, in 1961; the killing of the captive guerrilla leader Ernesto Che Guevara in Bolivia, on the orders of the CIA, in 1967; the death - apparently by suicide - of Chile's president, Salvador Allende, in the Pinochet-led coup of 1973.

None of these incidents had consequences as momentous as those of 1881, 1914 or 1994, but they revealed the violence that confrontational superpowers sanctioned outside their core domains.

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Today, almost 16 years after the Cold War's end, can new information resolve, or at least broaden, understanding of some of these killings? In relation to some of the more spectacular incidents - the Kennedy assassination or the plane crash that killed President Zia ul-Haq of Pakistan in 1988 - little has been added to the sum of knowledge.

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But new information has come to light about other murders and deaths during the 45-year global freeze. Dag Hammarskjold, the United Nations secretary-general killed in 1961 in the Congo, was in a plane that crashed as Belgian agents, working to split Katanga from the Congo, tried to force the pilot to land it. The kidnapping and killing of the Moroccan socialist leader Mehdi Ben Barka, when he was working with the Vietnamese and Cubans to launch the Tricontinental Organisation in Havana, has often been attributed to the CIA and Mossad, but Ben Barka seems to have been the victim of Morocco's security chief, Mohamed Oufkir. It was revealed that Georgi Markov, the Bulgarian dissident who became a BBC journalist in London and was stabbed with a poisoned umbrella on Waterloo Bridge in 1978, was killed by an Italian contracted by the Bulgarian intelligence services.

Haile Selassie, the veteran Ethiopian emperor, was last seen being bundled into a Volkswagen by revolutionary army officers in 1974. It is now known that his successor, Mengistu Haile-Mariam, had him killed in captivity and his body buried underneath the palace lavatory that the military dictator used.

The biography of Mao Tse-tung by Jung Chang and my brother Jon Halliday contains fascinating, macabre revelations about the death of three of Mao's most important opponents within the Chinese Communist Party leadership.

Liu Shao-chi and P'eng Te-huai were imprisoned, tortured and left to die in misery and obscurity; their deaths were concealed from the Chinese people as long as Mao lived. Lin Piao, at one point Mao's chosen successor, sought to flee to Russia after a failed coup attempt; his hurried commandeering of a Trident jet with insufficient fuel led to a crash in Mongolia. Meanwhile, US National Security Agency intercepts of Chinese radio traffic during the Tiananmen massacre of 1989 indicate that the situation was even more confused than appeared at the time and that the Chinese army did have a clear plan to kill students protesting in Beijing's central square.

The mid-1970s inaugurated a period of superpower negotiation known as detente. But it was also a moment when the collateral damage of violent (and, for a time at least, unexplained) deaths impacted intensely on those of us engaged in the political arguments of the period. There was Orlando Letelier, Chile's former foreign minister, exiled by Pinochet's coup and director of Washington's Institute for Policy Studies (for which I then worked). He was blown up with a colleague, Ronni Moffitt, on the way to work in 1976 as the result of collaboration between the Chilean secret police and Cuban and American right-wing extremists. Malcolm Caldwell, a lecturer in South-East Asian studies at the School of Oriental and African Studies in London, was killed in Phnom Penh in 1978, on the eve of the Vietnamese invasion of Cambodia. Ruth First, a South African Marxist scholar and writer, was killed in Maputo by a parcel bomb sent by Pretoria's security services in 1982.

How far any of the Cold War's individual deaths, assassinations and killings altered the war's course is debatable. The full facts about some of these murders may never be known. It may also be that the incidents with longer term effects are not always the most spectacular. When Akbar Khyber, an Afghan communist, died in April 1978 during a demonstration in Kabul, few people noted the incident, but it sparked the communist seizure of power a few days later. And when Nur Muhammad Taraki, the Afghan communist leader, was smothered by his sinister rival, Hafizullah Amin, in 1979, it persuaded a doddering Leonid Brezhnev to order the Soviet invasion in which Amin himself was killed - and which provoked the militant jihadi campaign of the 1980s.

Then there was Abdullah Azzam, a Palestinian Islamist leader, who was killed with his two sons by a car bomb in Pakistan in 1989. Few noticed at the time. Azzam both controlled the jihadi forces who had fought in Afghanistan and opposed the extension of the Islamist war to targets in the non-Islamic world, unlike his then-protege Osama bin Laden. Whether or not his subordinate organised the killing, it was Azzam's death that delivered leadership to bin Laden, and thus opened the door to September 11, 2001 and all that has followed.

Fred Halliday is professor of international relations, London School of Economics. This is an edited version of an article published at openDemocracy.net

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