Marxist radicalism, protest, and terrorist violence. The Economist describes it as "the gunshot that hoaxed a generation". The surviving Stasi Records contain no evidence that Kurras was acting under their orders when he shot Ohnesorg. Operation Infektion—The Stasi helped the KGB to spread HIV/AIDS disinformation that the United States had created the disease. Millions of people around the world still believe these claims. Sandoz chemical spill—The KGB reportedly ordered the Stasi to sabotage the chemical factory to distract attention from the Chernobyl disaster six months earlier in Ukraine. Investigators have found evidence of a death squad that carried out a number of assassinations (including assassination of Swedish journalist Cats Falck) on orders from the East German government from 1976 to 1987. Attempts to prosecute members failed. The Stasi attempted to assassinate Wolfgang Welsch, a famous critic of the regime. Stasi collaborator Peter Haack (Stasi codename "Alfons") befriended Welsch and then fed him hamburgers poisoned with thallium. It took weeks for doctors to find out why Welsch had suddenly lost his hair. Documents in the Stasi archives state that the KGB ordered Bulgarian agents to assassinate Pope John Paul II, who was known for his criticism of human rights in the Eastern Bloc, and the Stasi was asked to help with covering up traces. A special unit of the Stasi assisted Romanian intelligence in kidnapping Romanian dissident Oliviu Beldeanu from West Germany. The Stasi in 1972 made plans to assist the Ministry of Public Security (Vietnam) in improving its intelligence work during the Vietnam War. In 1975, the Stasi recorded a conversation between senior West German CDU politicians Helmut Kohl and Kurt Biedenkopf. It was then "leaked" to Stern magazine as a transcript recorded by American intelligence. The magazine then claimed that Americans were wiretapping West Germans and the public believed the story. Fall of the Soviet Union Recruitment of informants became increasingly difficult towards unification, and after 1986 there was a negative turnover rate of IMs. This had a significant impact on the Stasi's ability to survey the populace in a period of growing unrest, and knowledge of the Stasi's activities became more widespread. Stasi had been tasked during this period with preventing the country's economic difficulties becoming a political problem, through suppression of the very worst problems the state faced, but it failed to do so. On 7 November 1989, in response to the rapidly changing political and social