Iran Hostage Crisis: American AND Soviet Embassies?

I was reading up on the Iranian Hostage Crisis of 1979, and I read that the Ayatollah Khomeini had proposed a simultaneous siege of both the American and Soviet embassies in Tehran. IOTL, they only besieged and took hostages from the American embassy, but what if they simultaneously did so at the Soviet embassy as well? Would the Soviets go as far as invading Iran? As tempting as the thought of a joint American-Soviet invasion during the middle of the Cold War is, I can't see U.S. President Jimmy Carter ordering an invasion of Iran, unless we go back and have Ronald Reagan elected President in 1976.
 
I was reading up on the Iranian Hostage Crisis of 1979, and I read that the Ayatollah Khomeini had proposed a simultaneous siege of both the American and Soviet embassies in Tehran. IOTL, they only besieged and took hostages from the American embassy, but what if they simultaneously did so at the Soviet embassy as well? Would the Soviets go as far as invading Iran? As tempting as the thought of a joint American-Soviet invasion during the middle of the Cold War is, I can't see U.S. President Jimmy Carter ordering an invasion of Iran, unless we go back and have Ronald Reagan elected President in 1976.

That would be very interesting.
 
With the Soviet Embassy over run and hostages taken, prominent Iranian revolutionaries and THEIR FAMILIES start unmysteriously dieing at an alarmingly high rate due to lead poisoning and other unmysterious non-accidents.

Even with Carter in the White House, I don't see the Soviets risking US response to a military entry into Iran. Too important geo-carbon politically. Sure, lots of divisions sent to the border. That would make the KGB/GRU/Spetsnaz special ops look all the more intimidating to the Revolutionary leadership.

Simply no way a joint US-USSR military operation.

Interesting side effect might be no Invasion of Afghanistan. Hostage situation started November of 79. Invastion started December of 79. Troops being allocated for Afghanistan could likely be the one's shifted to the Iranian border.
 
Top