Glomar response

In United States law, the term Glomar response (aka Glomarization or Glomar denial) refers to a “neither confirm nor deny” (NCND) response to a Freedom of Information Act (FOIA) request. There are two types of instances in which a Glomarization has been used. The first is in a national security context, where to deny a request on security grounds would provide information that the documents or programs which the requester is seeking indeed exist. Glomarization is also used in the case of privacy

Source: Glomar response – Wikipedia