Naval War College Review
Defensive alliances are formed to deal with threats which the participants perceive to be common to them all.
DePorte, A. W.
"The North Atlantic Alliance: External Threats and Internal Stress,"
Naval War College Review: Vol. 37:
6, Article 8.
Available at: https://digital-commons.usnwc.edu/nwc-review/vol37/iss6/8