The Almanac of World Military Power by Trevor Nevitt Dupuy (1980, Hardcover, Subsequent Edition)

I recommend this book for someone who would like to know what the military might was at the height of communism. The late 70's was marked with how for the first time, the communist block compared to the western block in terms of population. It's hard to conceive what effect the Warsaw Pact had in the world long after it's been dissolved. I was able to see which where the most critical zones for each country. One example is how Sweden's military is so focused on the security of Gotland and the north and how it would expect to take Åland if Soviet Union were to attack Finland for its national security and deny it to the Soviets rather than to take it away from Finland