Change-iff
From FreeSpace Wiki
change-iff Change IFF (Action operator) Sets the specified ship(s) or wing(s) to the specified team. Takes 2 or more arguments... 1: Team to change to ("friendly", "hostile" or "unknown"). Rest: Name of ship or wing to change team status of.
The change IFF sexp can be used by mission designers so that when called, It will change the IFF of a given ship so that it can effectively change alliegance.
It can also be used to change the Players IFF simulating desertion or Commands wrath at messing up in some way.