In the 1980s, President Reagan authorized, as part of his big armed forces buildup, a plan known as the 600-Ship Navy. Most of us know about it, and Reagan's plan had a major effect. The USN went from 330 vessels in 1978 to 588 in 1988, which means he came close to making it.
Challenge: Build the United States Navy to 600 vessels. POD is any time after 1945. To win the challenge though, the Navy must still have 600 or more commissioned vessels in 2010.
Big Challenge: Increase the number to 750 vessels at any point, with 600+ still in the commission in 2010.