A possible assassination conspiracy was hatched in America when UK's Queen Elizabeth II visited the US in 1983.
This has been revealed in documents released by USA's premier probe agency FBI, as per a BBC report.
The alleged plot had come to light when an officer visited an Irish pub. He was told by a man that he wanted revenge for his daughter who was "killed in Northern Ireland by a rubber bullet".
The possible attack points would have been Golden Gate Bridge or Yosemite National Park.
The 1983 visit eventually went ahead as planned.