With a trial of General Augusto Pinochet increasingly unlikely here, victims of the Chilean military's 17-year dictatorship are now pressing legal actions in both Chilean and American courts against Henry A. Kissinger and other Nixon administration officials who supported plots to overthrow Salvador Allende Gossens, the Socialist president, in the early 1970's.

In perhaps the most prominent of the cases, an investigating judge here has formally asked Mr. Kissinger, a former national security adviser and secretary of state, and Nathaniel Davis, the American ambassador to Chile at the time, to respond to questions about the killing of an American citizen, Charles Horman, after the deadly military coup that brought General Pinochet to power on Sept. 11, 1973.

General Pinochet, now 85, ruled Chile until 1990. He was arrested in London in 1998 on a Spanish warrant charging him with human rights violations. After 16 months in custody, General Pinochet was released by Britain because of his declining health. Although he was arrested in Santiago in 2000, he was ruled mentally incompetent to stand trial.

The death of Mr. Horman, a filmmaker and journalist, was the subject of the 1982 movie "Missing." A civil suit that his widow, Joyce Horman, filed in the United States was withdrawn after she could not obtain access to relevant American government documents. But the initiation of legal action here against General Pinochet and the declassification of some American documents led her to file a new suit here 15 months ago.

William Rogers, Mr. Kissinger's lawyer, said in a letter that because the investigations in Chile and elsewhere related to Mr. Kissinger "in his capacity as secretary of state," the Department of State should respond to the issues that have been raised. He added that Mr. Kissinger is willing to "contribute what he can from his memory of those distant events," but did not say how or where that would occur.

Relatives of General René Schneider, commander of the Chilean Armed Forces when he was assassinated in Oct. 1970 by other military officers, have taken a different approach than Mrs. Horman. Alleging summary execution, assault and civil rights violations, they filed a $3 million civil suit in Washington last fall against Mr. Kissinger, Richard M. Helms, the former director of the Central Intelligence Agency, and other Nixon-era officials who, according to declassified United States documents, were involved in plotting a military coup to keep Mr. Allende from power.

In his books, Mr. Kissinger has acknowledged that he initially followed Mr. Nixon's orders in Sept. 1970 to organize a coup, but he also says that he ordered the effort shut down a month later. The government documents, however, indicate that the C.I.A. continued to encourage a coup here and also provided money to military officers who had been jailed for General Schneider's death.

"My father was neither for or against Allende, but a constitutionalist who believed that the winner of the election should take office," René Schneider Jr. said. "That made him an obstacle to Mr. Kissinger and the Nixon government, and so they conspired with generals here to carry out the attack on my father and to plot a coup attempt."

In another action, human rights lawyers here have filed a criminal complaint against Mr. Kissinger and other American officials, accusing them of helping organize the covert regional program of political repression called Operation Condor. As part of that plan, right-wing military dictatorships in Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay coordinated efforts throughout the 1970's to kidnap and kill hundreds of their exiled political opponents.

The most adverse exposure was a series of revelations about more than ten years of CIA interference in Chile, from 1963 to 1973. This was one of the most massive campaigns in US intelligence annals. The earliest effort was an attempt to shape the outcome of the 1964 presidential election in Chile, when the CIA underwrote more than half of the expenses of the Christian Democratic Party's campaign. This support was directed at defeating the communist candidate, Salvador Allende. It was probably not known to the Christian Democratic candidate, Eduardo Frei. In addition to funding Frei, the CIA waged an extensive anticommunist propaganda campaign, using posters, the radio, films, pamphlets, and the press, to convince the Chileans that Allende and communism would bring to their country Soviet militarism and Cuban brutality. As part of this campaign, hundreds of thousands of copies of an anticommunist pastoral letter of Pope Pius XI were distributed. Frei won handily, but allegations of CIA involvement seeped out.

As a result, the CIA was reluctant to play as large a role in the next Chilean presidential election, in 1970. Not only was its role smaller; it did not support a specific candidate. The effort was directed strictly against Allende and was based primarily on propaganda, employing virtually all Chilean media and some of the international press as well. The program failed when Allende won a plurality, though not a majority, of the popular vote.

Under Chilean electoral law, that threw the choice to a joint session of the legislature some seven weeks later. At the direction of the White House, the CIA moved to prevent the selection and inauguration of Allende. It attempted to induce his political opponents to manipulate the legislative election up to and including a political coup. Some 726 articles, broadcasts, editorials, and similar items were sponsored in the United States and Chile, and many briefings were given to the press. One of those, to Time magazine, reversed the magazine's attitude toward Allende. The overall effort failed, however, because of the unwillingness of the appropriate Chilean politicians to tamper with the constitutional process. Complementing the CIA effort, the US government exerted economic pressure on Chile, again to no avail. A second approach, entirely under CIA auspices, encouraged a military coup.

President Richard Nixon directed that neither the Departments of State and Defense nor the US Ambassador to Chile be informed of this undertaking. During a disorganized coup attempt that took place on October 22, the Chief of Staff of the Chilean Army was murdered. The CIA had originally encouraged the group responsible, but sensing that this group was likely to get out of control, the Agency had withdrawn its support a week earlier.

Allende was installed as President on November 2. Over the next three years, until 1973, the National Security Council authorized the CIA to expend some $7 million covertly to oppose Allende with propaganda, financial support for anti-Allende media in Chile, and funding for private organizations opposed to Allende. Other agencies of the US government applied economic and political pressure. On September 11, 1973, the Chilean military staged a coup in which Allende died, reportedly by suicide. The CIA did not sponsor this coup, but how much its encouragement of the 1970 coup and its continued liaison with the Chilean military encouraged the action is honestly difficult to assess. With Allende gone, the decade-long covert action program was phased out.

More was at stake, though, than covert action in Chile. The coup-related deaths in both 1970 and 1973 and the exposure of the role of the United States in helping to topple a democratically elected government, albeit a Marxist one, brought intense scrutiny to the ethics of using covert action to change the political complexion of other countries. As a result, such covert action came to a near halt by the mid 1970s.

A judge in Santiago has drawn up a list of questions for the US statesman and Nobel laureate, Henry Kissinger, about the 1973 killing of the American journalist Charles Horman, whose execution by forces loyal to General Augusto Pinochet was dramatized in the Hollywood film, Missing.

The questions, drawn up by the investigating magistrate Juan Guzman and lawyers for the victims of the Pinochet regime, were submitted to Chile's supreme court, which must now decide whether to forward them to the United States.

The list is under seal but it is thought to cover the extent of Mr Kissinger's knowledge of the Horman case. Horman's family have repeatedly claimed that the Nixon government, in which Mr Kissinger was national security advisor and secretary of state, knew more about what happened when the journalist was murdered in Chile than it has ever admitted.

Mr Kissinger, awarded the Nobel peace prize for his role in bringing the Vietnam war to an end, is now under increased scrutiny for his leading role in a number of controversial US actions abroad, including the bombing of Cambodia and Washington's support for authoritarian rightwing governments such as Gen Pinochet's.

Charles Horman's widow, Joyce, said yesterday that Mr Kissinger was "ultimately the one who has to answer the questions for the disappearance of my husband".

She added: "He was really calling the shots, as far as I'm concerned, in questions of state and the CIA, with regard to the protection and knowledge of what happened to Americans there." Encouraged by the success of international human rights cases against Gen Pinochet and Balkan war crimes suspects, human rights activists have recently drawn up allegations against Mr Kissinger. While visiting Paris in May, Mr Kissinger was subpoenaed by a French judge to answer questions about the death of French citizens under the Pinochet regime. Mr Kissinger refused to appear in court to answer the questions, saying he had a prior engagement.

This year, a Washington-based British journalist, Christopher Hitchens, published The Trial of Henry Kissinger, in which he accused the veteran proponent of realpolitik of conspiring to sabotage 1968 Vietnam peace talks and pursuing an illegal war in Cambodia, among other charges. Mr Kissinger called the book "contemptible".

In America, the danger is not that too much is remembered of the Pinochet era but that too much of the American role in helping to foment those old horrors may be forgotten.

There is a deceptively comforting story line that sequesters the present from the past, disguising any continuity between the regime change produced in Chile on Sept. 11, 1973, and other American experiments of that nature. In that reassuring historical narrative, Pinochet was perhaps guilty of trampling on democratic niceties and of kidnapping, torturing, and killing socialists and Marxists , but he represented, after all, the lesser of two evils. The alternative evil was commonly depicted as Soviet influence, left-wing radicalism, the expropriation of private property, and falling pro-American dominoes across Latin America.

The former US ambassador to the United Nations, Jeane Kirkpatrick, who passed away three days before Pinochet, once propounded a theory to justify American backing for military dictatorships in Latin America. Her rationale rested upon a distinction between totalitarian states like those in the communist world and mere authoritarian regimes. The latter were supposed to be more tolerable because, in contrast to the communist states, they left open the possibility of eventually permitting a return to democracy. It was a theory that failed the test of time, as demonstrated by the nearly bloodless implosion of communism and the flowering of democracy in Poland, Hungary, and the former Czechoslovakia.

Reflecting the spirit of such Cold War notions, a CIA document from the month after Allende was elected president on Sept. 11, 1970, says, "It is firm and continuing policy that Allende be overthrown by a coup" and "it is imperative that these actions be implemented clandestinely and securely so that the USG" - US government - "and American hand be well hidden." Whatever the details of US complicity in Pinochet's eventual seizure of power, Americans must not forget that their own democratic leaders share complicity in the disappearances, torture, and killings perpetrated after 1973 by their man in Chile.

The human-rights abuses committed under Pinochet's military junta were widely known throughout the country.

Rights groups estimate that more than 3,000 people were killed after 1973 when Salvador Allende, the democratically elected president, was overthrown and allegedly took his own life with a gun given to him by his friend, Fidel Castro.

Most of the murders took place in the first year of military rule, when Santiago's National Stadium was turned into a detention and torture centre.

Pinochet was facing charges over the "Caravan of Death" in 1973, when it is alleged a military death squad rounded up suspected leftists from prisons around the country and murdered them.

However, it was not such abuses that led to his support eroding - it was allegations of corruption, in 2005, when undeclared foreign bank accounts containing some £15 million were traced to him and members of his family.