instigator

US /ˈɪn.stə.ɡeɪ.t̬ɚ/
UK /ˈɪn.stə.ɡeɪ.t̬ɚ/
1.

kẻ xúi giục

a person who causes something to happen, especially something bad:

:
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The instigators of the disturbance have not yet been identified.