Under Operation Switchback in 1963, various programs intially
operated by the Central Intelligence Agency were handed over to
Military Assistance Command Vietnam (MACV).  Perhaps most notable had
been the Civilian Irregular Defense Group (CIDG Program).
MACV was intent on creating action elements out of these essentially
defense oriented arms, including the Mobile Strike Force.
*
The Mobile Strike Force (MSF or MIKE Force) appeared in December
1966, and was designed to provide both a direct action arm
and a reaction force for local operations in the vicinity
of its associated Special Forces camp.  An official table of
order and equipment existed, but from most evidence was rarely
followed.  As a result the weapon platoon element fluctuated
wildly from unit to unit, and some units even featured
recon elements akin to the Mobile Guerrilla Forces that
were eventually absorbed into the MSFs.
*
Organizations provided here are approximations based on
available evidence.