If memory serves, that's what GDW's Third World War wargame series postulated: Iranian civil strife after Ayatollah Khomeni's death results in both superpowers' intervening. From there, US and Soviet forces come into contact, and shortly after that the European mobilizations occur, and the Soviets launch an attack, either to salvage the position, pre-empt a NATO attack, or for some other reason.

Exactly: I have those games. There was one thing, IMHO, that GDW got wrong: the Iranian AF wouldn't have sided with the mullahs. Too much bad blood between them. The AF would've sided with the Regular Iranian Army.

A Soviet move into Iran and spillover into Europe is very possible.

There's actually a re-issue of the games due out later this year, with shiny new components. Maybe they'll have changed that bit.

I'd always thought you might be able to use the games to set up a Twilight: 2000 campaign, except that the game stops after a comparatively short eight to twelve one-week turns following the beginning of the European war.

I'm currently reading "When the world seemed new: George H W Bush and the end of the Cold War", and I'm just past the chapter on German reunification, 1989-90. No one knew how a war might start in East Germany, but everyone seemed aware that it was a possibility.

I wonder if we put together some violence breaking out (East German civilians vs a Soviet Army or KGB post, shooting starts... ) and cooler heads than Bush and Gorbachev present, and stuff goes downhill quickly. You'd still need a stronger USSR than the RL one in 1989, and a war that drags on for years, but not all the way until 2000.