As of February, 1971, legislation was passed in the United States
prohibiting continued cross-border operations into Laos and Cambodia.
As a result the task of cross border reconnaissance previously conducted
under Operation Nickle Steel (formerly Shining Brass) in Laos and under
Operation Salem House (formerly Daniel Boone) in Cambodia were passed to
the South Vietnamese Strategic Technical Directorate (STD), the South
Vietnamese counterpart to Military Assistance Command Vietnam's
Studies and Observation Group.  Operations in Laos were subsequently
conducted under Operation Phu Dung and in Cambodia under Operation
Thot Not.