Ronald Reagan’s unveiling of SDI became a burden on efforts to re-establish national security policy consensus in Denmark and Norway. The political parties had a widespread negative view of SDI and a fear of the initiative leading to a dangerous new arms race but disagreed on how to promote this view. Considerations for the United States, critical opposition parties and different views within the coalition governments caused the centre-right governments to pursue a policy of low-voiced scepticism, arguing it would be most influential. Being aware that their opposition was unlikely to have an effect on the US administration, the social democratic parties suggested a policy of outspoken opposition as they found it important to manifest their disapproval of the project. The exceptional parliamentary situation in Denmark and the change of government in Norway resulted in the two countries ‘footnoting’ NATO communiqués regarding SDI in 1986. This chapter shows in detail how and why international and domestic causes shaped Danish and Norwegian SDI policies.