UrsaMajor--there have been many irregular forces made up of soldiers in history. It isn't what the unit is, or who is in it, it is how the unit acts and is utilized. Historically some main line units have switched back and forth between regular and irregular styles of fighting--it is a mission, a mindset and objective thing.

I agree with many here in that it is the seeming need of western forces (perhaps all industralized militaries) to specialize and over specialize that prevents the flexibility of a multipurpose unit. It is almost as if we have a hidden referee waiting behind a bush who will jump out and penalize us "hey you, yeah you regular infantry that mission appears too much like a SOF mission, go to the penalty box for 5." Specialization has made us very good but the associated compartmentalization and turf wars have been detrimental to overall flexibility and coordination.