Queen Elizabeth.Photo:Tim Graham Photo Library via Getty

The Queen Makes A Speech At A Banquet At The De Young Museum Wearing A Dress With Bows And Frills

Tim Graham Photo Library via Getty

The FBI was aware of frightening threats againstQueen Elizabethduring her tour of California 40 years ago.

Queen Elizabeth, Prince Philip, President Ronald Reagan and Nancy Reagan.David Levenson/Getty

Queen Elizabeth II and Prince Philip, Duke of Edinburgh entertaining President Ronald Reagan and Nancy Reagan on board HMY Britannia on March 4, 1983 in San Francisco harbour, California, USA. Queen Elizabeth II was on a Royal Tour of the USA.

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Queen Elizabeth.David Cairns/Getty

Queen Elizabeth II jumps ashore from a barge after disembarking from the Royal Yacht ‘Brittania’ during a State Visit to Turkey, 23rd October 1971.

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President Ronald Reagan and Queen Elizabeth.Tim Graham Photo Library via Getty

The Queen With President Reagan At A State Banquet At Windsor Castle.

The files added that authorities planned to contact the patron, “who has been interviewed in PIRA cases and has been generally cooperative, although he makes no secret of his sympathies for the IRA.”

The royal visit to the U.S. came during the Troubles, the 30-year conflict in Northern Ireland that divided unionists and nationalists over whether Northern Ireland should stay within the U.K. or join the Republic of Ireland, theBBCreported. Groups from both sides like the IRA and Ulster Volunteer Force carried out attacks, and British troops were deployed to Northern Ireland.

Queen Elizabeth.Anwar Hussein/Getty

Queen Elizabeth ll looks at the views at Inspiration Point in the Yosemite National Park during a Tour of the USA on March 05, 1983 in Yosemite, California, USA.

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Despite the threat, the FBI reported that Queen Elizabeth’s visit to California wrapped “without incident,” and the case was closed.

Elsewhere in the extensive file, before the Queen visited Kentucky in 1989, the FBI noted that “the possibility of threats against the British monarchy is everpresent from the Irish Republican Army.” Two years later, in 1991, the federal law enforcement agency was on alert for protests when she attended a Baltimore Orioles game with President George H.W. Bush.

source: people.com