敌我 almost always appears in fixed phrases:
敌我矛盾 (díwǒ máodùn — 'enemy-versus-us contradictions,' a Maoist political category for antagonistic class conflict),
敌我不分 (failing to tell friend from foe),
敌我识别 (military IFF — Identification Friend or Foe). It carries strong us-vs-them framing.