The FBI has released documents detailing a potential threat to Queen Elizabeth II during her 1983 visit to the United States, which reveal that an unidentified San Francisco police officer received a tip about the plot to assassinate the Queen. The documents span over 100 pages and outline a serious threat made ahead of the Queen's visit, as well as safety concerns that came up in other visits the Queen made to the U.S. The documents do not reveal any further details about the potential threat, but do show that the FBI was aware of the potential threat and was taking steps to ensure the Queen's safety.