An investigation of the possible effects of climatic change on the military posture of the United States and the Soviet Union. The problem is to estimate worsening sea-ice conditions in the Norwegian, Barents, and White seas in the event of a climatic cooling during the next few decades. Future climatic conditions assumed for this study approximate the severe winters experienced during the Little Ice Age from the mid-1400s to the mid-1800s. A period of cooling in the polar regions implies a worsening of sea-ice conditions in the Arctic seas producing increased hazards to navigation. The author concludes that for a climatic state similar to the Little Ice Age, the Norwegian and Barents seas would remain open to navigation. Within the White Sea, however, under extreme conditions the duration of the ice season would lengthen to about eight months, with maximum ice thickness reaching 70 in.