Cause of Queen Elizabeth II's death revealed 0:43

(CNN) -- Britain's Queen Elizabeth II faced a possible assassination threat 40 years ago, ahead of a trip to the United States, according to newly released documents by the U.S. Federal Bureau of Investigation.

A 103-page set was published Tuesday on the FBI's online records site, The Vault. The files cover preparations for several trips the late queen made to the United States, including an official West Coast tour with her husband, Prince Philip, in 1983.

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One document appears to detail a tip collected about a month before that visit by San Francisco police in connection with a phone call from "a man claiming his daughter had been killed in Northern Ireland by a rubber bullet."

It continues: "This man further stated that he was going to attempt to harm Queen Elizabeth and that he would do so either by dropping an object from the Golden Gate Bridge onto the royal yacht Britannia when sailing underneath, or he would attempt to kill Queen Elizabeth when she visited Yosemite National Park."

The same document notes that it was "the intention of the Secret Service to close the Golden Gate Bridge walkways when the yacht approaches." There is no mention of any precautions that could have been taken in the national park, nor do the archives reveal whether any arrests were made.

The Queen also visited Yosemite National Park during her official 1983 tour. Credit: Tim Graham Photo Library/Getty Images

The files illustrate the FBI's hypervigilance for possible threats to the visiting British monarch, collaboration with the US Secret Service and concern for the Irish Republican Army (IRA) and its supporters during royal visits.


The Queen's cousin, Louis Mountbatten, was killed by the Provisional IRA in 1979, using a bomb planted on his fishing boat. Three other people, including two children, were killed in the same blast. Many of the queen's trips to the U.S. took place amid unrest in Northern Ireland and documents reveal the FBI closely monitored preparations for royal visits over the years.

Prior to a private visit to Kentucky in 1989, a document notes that, although the FBI was not aware of any specific threat to the queen, "the possibility of threats against the British monarchy is ever-present by the Irish Republican Army (IRA)."

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Elsewhere in the archives, a preparatory document for the Queen's 1991 state visit outlines concern for Irish groups organizing protests at several scheduled engagements, including a baseball game the monarch was due to attend and an event at the White House. Citing information printed in an Irish newspaper in Philadelphia titled Irish Edition, the page said: "The article claimed that anti-British sentiments are running high as a result of the injustices inflicted on the Birmingham Six by the corrupt English judicial system and the recent spate of brutal murders of unarmed Irish nationalists in the six boroughs at the hands of loyalist death squads."

He added: "Although the article did not contain threats against the president or the queen, the statements could be considered inflammatory. The article claimed that an Irish group had booked a large block of tickets for the main stand."

On another trip to the U.S., in 1991, President George H. W. Bush and First Lady Barbara Bush joined the Queen and Duke of Edinburgh at a baseball game in Baltimore. Credit: J. David Ake/AFP/Getty Images

Another document from the archive, dated July 1976, mentions an occasion when the queen traveled back across the Atlantic to help celebrate America's bicentennial, with stops in Philadelphia, Washington and New York.

During that trip, FBI documents reveal, a citation was issued to a pilot for flying over Battery Park with a small two-seater plane carrying a sign reading "England, get out of Ireland."

British Royal FamilyQueen Elizabeth II