Black bag job

A Black Bag Job or Black Bag Operation is a covert entry action undertaken by a police force or intelligence organization that relies on secrecy or deceit rather than violence or confrontation.

A classical black bag job might be the planting of surveillence equipment or the theft of documents by burglary.

The term comes from the black bags formerly used by intelligence services to carry the equipment required for such operations.

Reference

Sir Peter Wright. Spy Catcher: The Candid Autobiography of a Senior Intelligence Officer. Penguin USA, 1987. ISBN 0670820555.