Fleshing out the victory conditions, objectives, and context a bit more....
Strategic Context
Political
Recent US and Israeli intelligence reports indicate that Iran has taken advantage of relaxed foreign scrutiny of its nuclear programs to restart its nuclear weapons program. Further, as the US "surge" in Iraq is subsiding, Iran appears to be increasing its aid to the insurgency in an attempt to create a counteroffensive. The US President has asked Congress for authorization to use military force against Iran. Congress will be voting on the issue shortly, and the resolution is expected to pass by a narrow margin. Once such authorization is obtained the President is expected to make a final push for a diplomatic settlement before launching an air war against Iranian nuclear facilities and bases associated with support of insurgents.
In Iraq, the political gains of the troop surge are beginning to be realized. Baghdad has passed landmark legislation curtailing much of the excessive lustration policies handed down by the CPA and is successfully administering a national budget. Much national infrastructure has been rebuilt. Continued sectarian violence, however, has prevented the Sunni and Shia from fully trusting each other, and there remains a constant threat of a pullout from the Baghdad government.
Military
The situation in Iraq has been deteriorating in recent weeks due to increased attacks. Coalition leaders strongly suspect that the majority of the upswing has been caused by an increase in foreign fighters and supplies coming into Iraq. There has been some concern that current (post-surge) troops levels are inadequate to deal with the situation, but the Pentagon has insisted that it has enough troops.
Tensions with Iran have led to a quiet influx of forces into the Gulf region to prepare for the possibility of war. The buildup is not yet complete. At current force levels, the US would not be able to protect its assets in the theatre from ballistic missile attack, nor does it have enough ground forces in Iraq to deal with both the insurgency and an Iranian conventional counteroffensive, nor can it assure the safety of merchant shipping through the Persian Gulf. This situation is quickly changing, however, and soon the Coallition will have a robust defense against possible Iranian counterattacks.
Strategic Objectives
Coalition: Avoid war with Iran by compelling a diplomatic settlement on US terms.
Iran: Avoid war through deterrence of the US (or its coalition partners).
Both: Maintain safety of commercial shipping
The political and military situation on its current trajectory will lead to a Coalition victory. Iran must change that trajectory; the Coalition must maintain it. If Iran cannot change the trajectory, then it has the option to force a mutual loss by disrupting shipping in the Gulf.
Operations
Coalition:
1. Move TBMD ships into position to protect Coaltion bases
2. Safely deliver additional land forces to Iraq
3. Prevent the smuggling of supplies to the Iraqi insurgency
4. Locate and hold at risk Iranian platforms capable of attacking commercial shipping
5. Preserve military assets in the region.
Iran:
1. Prevent deployment of TBMD ships.
2. Prevent arrival of additional land forces to Iraq
3. Increase the strain on US ground forces in Iraq due to insurgent operations
4. Maintain a credible threat against US interests in the region, including commercial shipping, oil platforms, and military assets.
5. Preserve military assets in the region.
Evaluating Success using Objectives
Scoring system:
I can think of two ways to do this. One is to create a number of scales (e.g. political/military, SLOC security) and to have goal triggers associated with objectives pertaining to those scalese. The names of the triggers would include a point value and a direction (e.g., "Pol/Mil: 100 Iran"). At the end of the scenario, players would have to manually calculate where on the scales the scenario ended at, and they would reference that against specified victory conditions.
Another way would be to use a complex system of aggregate triggers that effectively total up the points automatically. The advantage of this, in addition to the obvious ease to the players, is that it can be made "spoiler free"--a player will not be put on notice through the status screen that his/her opponent has completed an objective. The players won't know unless the completion was observed by the players themselves, or unless an intelligence message lets them know. The downside of this is that there may end up being a rather large combination of possible outcomes, which means there could be a lot of triggers involved. They'd also be very hard to troubleshoot.
Possible Objectives and effects
1. Delivery of land forces not completed: US less able to deal with insurgency/Iranian counterattack; Iran's position enhanced
2. Port mined: Potential "natural consequences."
If discovered, may cause disruption of shipping. Ships intended to arrive at that port may be ordered to stop until port is cleared (see #1)
3. Minesweeper destroyed/sabotaged: see #2.
4. Spec ops delivered to port: port facilities sabotaged/bombed, causes economic disruption; or, suicide fishing boat squad formed
5. High value miltiary target sunk/sabotaged (e.g., command ship in port): degraded military capability in region
6. Spec ops delivered to coast: delivery of supplies to insurgents, increased strain on coalition ground forces
7. Smuggling ship safely slips by coalition forces: same as #6.
8. SM-3 TBMD ship damaged/sunk: degraded defense capability
9. Boarding team/downed pilot captured: reduced US political will, likely delay in any operations to secure safe return
10. Spec ops delivered to oil platform: hostage situation, US more cognizant of vulnerability, decreased political will, economic disruption; or, platform bombed/sabotaged, economic disruption
11. Merchants sunk: economic disruption; perhaps additional damage if outgoing tanker (oil spill). Possible reassignment of Coalition assets.
12. Coalition combat losses (attributed to Iran): increased US anger, less Iranian doubt that US is willing to go to war (may also have pro-Iran consequences depending on the platform destroyed, see #1, #3, and #8).
You'll note that I'm already thinking in terms of two scales, Political/Military and Economic disruption. In this model, the Political/Military scale would have Iran on one end and the Coalition on the other. Scored in the middle of the scale would indicate neither side has a diplomatic advantage and that war is inevitable (mutual loss). The economic scale would progress from having no effect to causing a mutual loss.