Supposing in WWII, the W Allies decide to not arm or aid the Soviets whether it’s just on ideological ‘we don’t want a powerful Soviet Union in Europe’ level or worse, the Allies initially declared war on the Soviets for attacking Poland/Finland but it’s more of a phoney war where technically they’re at war but neither really wants to fight (esp. once Germany backhands the Soviets in 1941)....
Do you think Operation Unthinkable becomes more plausible?
There’s some details that you might have to consider like how well would the Soviets perform without lend lease (I doubt they’d collapse but I definitely see the second world war taking longer to end) or would we have to remove Roosevelt and replace him with an anti communist and so on?
But yeah, you think Unthinkable would be more likely if the Soviets weren’t treated as an Ally by the west? I think without or little dialogue on the post war map, the race for Berlin would be even greater and risk the chance of ‘friendly fire’ and that could prove either side the casus belli to declare war.