Perhaps the most difficult element in the complex development and implementation of national security policy is the necessary projection of future defense needs, often as much as 20 years hence.
Herzfeld, Charles M.
"The Challenges of Implementation of the National Security Policy,"
Naval War College Review: Vol. 28
, Article 4.
Available at: https://digital-commons.usnwc.edu/nwc-review/vol28/iss4/4