In the United Kingdom, D-Notices, officially known since 2015 as DSMA-Notices (Defence and Security Media Advisory Notices),[1] are official requests to news editors not to publish or broadcast items on specified subjects for reasons of national security.
DSMA-Notices were originally called Defence Notices (abbreviated to D-Notice) from their inception in 1912 to 1993, and DA-Notices (Defence Advisory Notices) from 1993 until the mid-2010s.
A similar D-Notice system was previously operational in Australia, but has fallen into disuse. Sweden maintained a similar "gray notice" system during World War II, as described below.