Washington ? As secretary of state, Henry Kissinger canceled a U.S. warning against carrying out international political assassinations that was to have gone to Chile and two neighboring nations just days before a former ambassador was killed by Chilean agents on Washington’s Embassy Row in 1976, a newly released State Department cable shows.

Whether Kissinger played a role in blocking the delivery of the warning against assassination to the governments of Chile, Argentina and Uruguay has long been a topic of controversy.

Discovered in recent weeks by the National Security Archive, a nonprofit research organization, the Sept. 16, 1976, cable is among tens of thousands of declassified State Department documents recently made available to the public.