Operation
From Navy.ca Wiki
A operation is the use of military resources to fulfill a specific mission objective or set of objectives. Operations are usually identified by specific code words (ie Operation APOLLO). These operations may or may not involved armed conflict with an opposing force. Operation PEREGRINE, for example, referred to the fighting of forest fires.
An Operation should not be confused with an Exercise, though both are identified by code names; an operation is based on achieving a specific real world mission.