Fears of false flag and foreign funded covert operations designed to influence US policy drove the Senate Foreign Relations Committee to launch exhaustive investigations and call for warranted enforcement of the Foreign Agents Registration Act (FARA).   A newly declassified March 17, 1961 memo unsealed and released by the National Archives and Records Administration on October 21, 2010 outlined the Senate's rational for investigating Israel lobbying groups and other foreign agents active across the United States:
 
"...In recent years there has been an increasing number of incidents involving attempts by foreign governments, or their agents, to influence the conduct of American foreign policy by techniques outside normal diplomatic channels..there have been occasions when representatives of other governments have been privately accused of engaging in covert activities within the United States and elsewhere, for the purpose of influencing United States Policy (the Lavon Affair)."
 
The Lavon Affair refers to a false flag Israeli terrorist bombing plot code named "Operation Susannah" against US targets in Egypt.  It was designed to reverse US policy pressuring British withdrawals and reverting control of the Suez Canal to Egypt.  Israeli agents infiltrating as Arabs were discovered, arrested and criminally prosecuted in Egypt when their explosives malfunctioned, leading to a crisis in the Israeli government.
 
The Senate Foreign Relations Committee, which mentioned Lavon twice in the three page memo, expressed concerns about investigating such sensitive matters.  "There would undoubtedly (even with care) be instances which would lead to foreign governmental protests, to violent attacks by special groups in the United States..."  The declassified files are now available at: http://www.irmep.org/ila/forrel 
 
Press Release: http://news.yahoo.com/s/usnw/20101109/pl_usnw/DC98078
Israel Lobby Archive:      http://www.IRmep.org/ila/forrel/