The shock compelled exercise planners to rig the rest of the war game for U.S. forces. Here's What You Need to Know: A weak opponent can exact a surprising cost on an arrogant foe. It’s worth recalling a 2002 Pentagon war game in which a U.S. Marine Corps played the part of an enemy commander waging a bloody defensive campaign against a much more powerful U.S. force. Lt. Gen. Paul Van Riper’s own hodgepodge of troops, ships and planes was similar in organization and capability to Iran’s actual forces. Van Riper’s success in blunting a simulated American assault could reveal how Tehran might fight in the real world.