In 1971, the FBI put John Lennon under surveillance due to his anti-war activism, and the Immigration and Naturalization Service attempted to deport him in 1972. Declassified FBI files revealed extensive monitoring of Lennon's activities, phone calls, and associations. The FBI fought for over 25 years to keep the files secret, with historian Jon Wiener suing under FOIA in 1983 and not receiving all files until 2006.