Wiktionary
n. A covert operation typically involving activities that are highly clandestine and outside of standard military protocol.
WordNet
n. a covert operation not attributable to the organization carrying it out
Wikipedia
A black operation or black op is a covert operation by a government, a government agency, or a military organization. This can include activities by private companies or groups. Key features of a black operation are that it is secret and it is not attributable to the organization carrying it out. The main difference between a black operation and one that is merely secret is that a black operation involves a significant degree of deception, to conceal who is behind it or to make it appear that some other entity is responsible (" false flag" operations).
A single such activity may be called a "black bag operation"; that term is primarily used for covert or clandestine surreptitious entries into structures to obtain information for human intelligence operations. Such operations are known to have been carried out by the FBI, the Central Intelligence Agency, Mossad, MI6, ISI (Pakistan), DGFI, RAW, MSS, and the intelligence services of other nations.
Usage examples of "black operation".
Nor did he look forward to flying on another goddamned airplane into a communist country with false identity papers and overseeing a black operation there—.
She's also a Canadian who was thoroughly messed up by a group of American assholes - mind you, he had no compunction at all using the word - in some kind of mentally deranged black operation - yes, that was the phrase he used, mentally deranged - an idiotic operation mounted by these same assholes - indeed, he repeated it - that has never been satisfactorily explained.
Or, if she was, it's some kind of black operation being done completely outside the Havenite command chain.
Or, if she was, its some kind of black operation being done completely outside the Havenite command chain.