Prefixes:
* Anti-: Opposing or against war (anti-war, anti-militarism)
* Beli-: Relating to war (bellicose, belligerent)
* Inter-: Between or among nations in war (inter-state war, inter-tribal conflict)
* Post-: After a war (post-war economy, post-traumatic stress)
* Pre-: Before a war (pre-war tensions, pre-emptive strike)
* Super-: Above or beyond war (superpower, super-weapon)
* Trans-: Across or beyond war (transnational conflict, transatlantic war)
Suffixes:
* -fare: The conduct of war (warfare, naval warfare)
* -monger: Someone who promotes or profits from war (war-monger, peacemonger)
* -time: Relating to a specific war (wartime rationing, wartime production)
* -torn: Divided or affected by war (war-torn country, war-torn landscape)
* -stricken: Afflicted by war (war-stricken nation, war-stricken people)
Other related terms:
* Arm-: Relating to weapons or the military (armament, arms race)
* Battle-: Relating to a fight or engagement (battlefield, battle cry)
* Conflict-: Relating to disagreement or struggle (conflict resolution, conflict zone)
* Hostile-: Relating to an enemy or warfare (hostilities, hostile takeover)
* Military-: Relating to the armed forces (military base, military strategy)
The best prefix or suffix for your particular use depends on the context and the meaning you wish to convey.