TOP SECRET ANNEX SOVIET THREAT TO NORTHERN SCANDINAVIA In assessing the threat to Northern Scandinavia as a result of war between the Western Powers and the Soviet Union, we consider that the threat cannot be regarded in isolation but should be treated as part of a probable Soviet campaign against Western Europe. Our appreciations of the likely form of operations against Scandinavia in 1951+ and 1954ø have already been prepared. We examine below the specific threat to Narvik. Climate 2. The most suitable period for air operations in Northern Scandinavia is from April to October, while June, July and August are the least disturbed months from the point of view of seaborne invasion.