先发制人

先发制人 [xiān fā zhì rén]

1. ■ strike first to gain the initiative; beat to the draw; dominate the enemy by striking first; fire the first shot; gain an advantage over a competitor [the enemy] without his knowing; gain mastery by striking first; get [have] the drop on sb.; get the upper hand by taking the initiative; steal a march upon [on] sb.; steal one's thunder; strike first to forestall the enemy; strike the first blow; take the wind out of sb.'s sails; The launcher has the advantage:

采取先发制人的手段 take preemptive measures;

如受威胁便发动先发制人的打击 launch a preemptive strike if threatened