Realize that you were framed for that crime
Escape military prison
Hide in LA with your old team
Dub yourselves an alpha-team
hire yourself out as mercenaries
Take control of Alcatraz Island.
Threaten city with unspecified missile doom unless demands are met.
Make unclear and surreptitious demands for metaphysical goals.
But yeah, that's the basic idea. You can die at random in the introduction, due to HMG fire from a surprise T-72.
The second mission has two optional leadins: Mission Sneak-Shoot-Sneak: You can run around at night as a "Special Forces" guy, with optional goals in the opposite direction of your real objective. Trying to accomplish the optional goal will get you shot in the face by soldiers who don't notice the lookouts being sniped, but will hear you trip over a tent-peg from a quarter mile away. Accomplishing the real objective, destroying an entire armor park by yourself, requires stealing explosive satchels, sneaking past patrols (which the same schizophrenic "stealth" system can screw over at any moment), and plant them under vehicles. You get a Javelin, but using it summons an attack helicopter to kill you and everyone you love and your escape boat. I managed to destroy four or five vehicles and book it, but apparently leaving one
Shilka standing isn't good enough - those jerks wouldn't even let me back in the boat while the Hatredcopter strafed us.
The other option is to climb a watertower, the perfect place to be blasted to bits, and snipe a troop convoy. Literally, you are entire mission, sit on a fucking target stand and get shot at. The main mission is actually running around in a squad, but I got stuck with the machinegun (with no replacement ammo around), which I still succeeded with. Private Gomer Pyle got the Javelin, which meant I got another facefull of bullets from a BMP he refused to shoot at before he died.
That's the other problem with "realistic" military games - in the real world, if the mission fails, the war goes on.