Shipbuilding has been one of the biggest conundrums of post-Cold War defense planning, and the Defense Department's confusion seems only to escalate as time goes by. In fact, you might argue that the shipbuilding plan is the most reliable measure of our strategic uncertainty; it's also a measure of how budgetary, industrial and domestic political concerns have hampered a genuinely strategic assessment of fleet requirements. Thus, the Navy's shipbuilding plans have changed on nearly an annual basis over the past 15 years.

http://www.armedforcesjournal.com/2006/07/1872661