I have no problems with any of the choices yall make, as long as yall still make the game
But couldnt yall escalade the seriousness of the situation to come up with a deeper background story? Like the U.S. have just launched a ground war into Syria, using the minimal amount of force to accomplish the job with less soldiers at risk. While in the ground war fighting syrians (breaking down terrorist organizations and cells holed up in Syria), the U.S. runs into stiff opposition and realize that the enemy are using some modern russian equipment (T-80's, T-90's, etc.). After a hasty retreat to regroup (the small american force is outnumbered), intel releases information that there has been an Iranian interdiction (They mobolized as fast as they could to catch the american forces off-guard). As the American force on the ground fight a defensive war, gradually being pushed back, the U.S. is mobilizing everything they can get their hands on. As more and more U.S. forces enter Syria, the tables start to turn as they push back the Iranian/Syrian forces. Then <insert some kind of war ending scenarios, like Iran being pushed across the border, or capture of a high ranking figure>.
So basically, small U.S. force fights and still outnumbers and outguns the Syrian forces (US on the offensive in the first part of the war). Interdiction by a major country in the surrounding area, using modern equipment, US forces outnumbered, matched in firepower, and fighting defensively. US mobolizes, outnumbers or matches combined major country/Syrian forces and go back on the offensive.
With this scenario, with the US being in trouble, you could even throw in some coalition forces units and missions as well (Americans not the big guys on the block in a war, BLASHPEMY ). Like canadians, germans or the british.
Just a thought.
P.S.- the first time I read the OP post, OPFORIA from Americas Army popped into my head .