This could in fact lead to a repetition of the mistakes of the past, when the paralyzed United Nations were, due to the small number and influence of neutral countries, a mere bystander to the risky arms-race fought out between the two nuclear superpowers.

repetition 是名词，来自动词 repeat（重复），表示"重复、重演"的行为或现象。前缀 re- 表示"再次"，词根 -pet- 来自拉丁语 petere（寻求、要求），所以字面意思是"再次寻求"，引申为"重复"。