AHC: Iran-Iraq War Escalates into World War III

With a POD no earlier than September 22, 1981, brainstorm a way for the Iran-Iraq War to escalate into the Third World War. Bonus points are rewarded if the Soviet Union and Iran are on the same side (in OTL the Soviets and the Americans both largely supported Iraq, but many of the Soviet client states in the Middle East favored Iran).

I would think the most likely scenario would be for the Soviets to invade Iran in support of the Iraqis, sparking a US intervention under Carter Doctrine.

This was evidently a fairly common trope in the 1980s - Harold Coyle's first two technothrillers (Team Yankee and Sword Point) and Robert McCammon's post-apocalyptic horror novel Swan Song all feature scenarios where the Iran-Iraq War leads to WW3 or (at least a major US-USSR confrontation).

Any ideas?
 
The Islamist Students take over the Soviet embassy in 1979 instead of the US one, sparking a hostage crisis with the USSR involved; the USSR has its own counterpart to Operation Eagle Claw which still fails just like the latter but this one prompts the leadership under Brezhnev to invade Iran and dispose the country of its Islamist leaders. Chaos ensues once the Soviet military forces invade and occupy most of Iranian soil in 1981 with Iraqi aid. From there you can pretty guess how crazy things can get until the incident spreads to Germany itself.
 
Top