[Raellus]

Perhaps Sweden somehow "provokes" the USSR to invade, maybe even unintentionally.

For example, say Soviet combat aircraft stray into Swedish airspace and the Swedes shoot them down; a Soviet ship or sub strays into Swedish waters and is sunk; Soviet troops accidentally cross the border and are killed or captured (or some combination of all three, over the course of the war to date).

The Soviets feel honor bound to send the Swedes a message and launch a punitive invasion thinking that it will cow the Swedes into a more submissive posture, but instead it triggers Swedish nationalism and Stockholm's invitation to NATO to send its own troops.

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