Starfleet Special Operations was a division within the Federation Starfleet.
In 2310, a contingent of Special Operations operatives, as well as a small group of Starfleet officers including John Harriman, Demora Sulu, Michael Paris, Creyn, Zultu Bini, Claudine Robinson, and T'Prel spent nearly three weeks on Devron II. (TLE novel: Serpents Among the Ruins)
In 2379, a contingent of Special Operations operatives was able to capture a Breen vessel in the Ravanar system, although their actions were officially denied by the Federation Security Council. Ambassador Worf was able to obtain these schematics to trade to Imperial Intelligence agent Lorgh in exchange for blackmail information against Klingon Councillor Kopek.
A few weeks later, Special Operations personnel were deployed to the beleaguered planet of Tezwa, where they operated under the direction of Security Chief Christine Vale and her deputy Jim Peart. Peart inadvertently led over a hundred SSO personnel to their deaths in an insurgent trap, and the loss weighed heavily on his psyche, eventually influencing his decision to resign his commission. (TNG novels: A Time to Kill, A Time to Heal)
- In most countries special forces (SF) is a generic term for highly-trained military units that conduct specialized operations such as reconnaissance, unconventional warfare, and counter-terrorism actions. (In the United States, the term Special Operations Forces (SOF) is used instead of special forces to refer to the aforementioned units because Special Forces refers to a specific unit, the United States Army Special Forces aka "Green Berets".)