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They might have mentioned Norway's involvement in Afghanistan as a motive but I doubt they actually blamed Afghanistan. And I don't think it's anything to do with Libya either, there's unlikely to be a pro-Gaddafi terrorist force bombing those who intervened in Libya and if there was the UK, France and the US would be far more likely targets.

If it is Islamic extremists who did this then Norway's military actions in Libya & Afghanistan might have been part of the motivation but you can't really say it was directly due to one of those two countries or an organisation from one of those two countries