The nation-state system (the society of states in which the United States forms a part) is a system which itself engenders international conflict; the conflict that arises out of it is not only inevitable but literally indispensable, because the system could not function without it.
Lerche, Charles O.
"The Nation-State System: A Source of Conflict,"
Naval War College Review: Vol. 11
, Article 3.
Available at: https://digital-commons.usnwc.edu/nwc-review/vol11/iss7/3