I never thought about it before but those 4 alien looking dudes with the rocket suit are the 4 Horsemen. Well I think they are the 4 Horseman.
Check them out in MGS2 Solid Snake:
They all have numbers on their heads 1, 2, 3, 4. They only took orders from the president but not anymore. Big Boss will become their Boss after he kicks their butt.
Looks like we will be forming that mercenary army and will be recruiting some of the MG2: Solid Snake bosses. Bring on