Book excerpt: Joshua M. Epstein argues that prevailing assumptions about the East- West balance of power rest on erroneous measures of military strength. He develops a method for analyzing military capabilities and applies that general procedure to the Soviet tactical air threat to NATO. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.