In most saboteur missions, the player is usually one of the saboteurs, on the offensive.
How about playing a regular NATO foot soldier, either on guard or in the elisted mens club or manning the communications center, etc., when suddenly the base's elictricity goes off (lights blink a few times - then pitch darkness), some faint shots are heard, followed by a powerful explosion.
Someone runs in to say the officer's club/barracks has been hit. You run over, the base commander is dying and, with his last breath, tells you to take command. (Gosh, I'm crying).
Your job is to find the saboteurs before they can cause more damage and capture them dead or alive. it's a moonless night and you don't know where in the world you're going to find NVG's, though the Spetsnaz have them, of course.