Its the symbols of the various Spartan fireteams in Spartan Ops.
Crimson = Sharks Majestic = Stingrays Ivy = Snakes Talon = Eagle Rhino = Rhino etc.
That's the the reasoning for it. In War Games, you're either playing as members of Majestic or Crimson team competing against each other. --- Underwater Spartans: http://www.youtube.com/watch?v=Djp5dtz02eQ&feature=plcp