To counter the growing threat of the Soviet navy, the Administration has announced its intention to reverse the long-term decline in the size of the U.S. Navy and otherwise improve Navy capabilities. It proposes to expand the U.S. fleet from the current 535 ships to roughly 600 and to increase the number of carrier-based air wings from 12 to 14. In addition to expanding, the Navy plans to modernize the existing carrier air forces, replacing 360 aircraft with more recent types, notably the F/A-18. This paper estimates the cost of the Navy's plan to expand and modernize its carrier air forces and examines alternatives to parts of that plan, while a companion Congressional Budget Office paper analyzes the shipbuilding issue.