black op

or black operation

noun
  1. Often black ops. a secret mission or campaign carried out by a military, governmental, or other organization, typically one in which the organization conceals or denies its involvement: Some national intelligence agencies use black ops to undermine enemy governments. The company even resorted to an industrial black op to steal secrets from its competitor.

Origin of black op

First recorded in 1940–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018