peacenik       
noun [ C ]  informal often disapproving uk/ˈpiːs.nɪk/ us/ˈpiːs.nɪk/
 反战分子
a person who opposes wars or a particular war and shows this by protesting
  A "peacenik" in his youth, he was once arrested for praying on the runway of a military air base.  他年轻的时候是一个“反战分子”,曾经因为在军事基地的跑道上祈祷而被拘捕。