During mid-October 2001 , members of 21 SAS and 23 SAS were deployed to Afghanistan as reinforcements of two squadrons of 22 SAS , for Operation Determine , during the 2001 coalition invasion of Afghanistan to '' topple '' the Taliban regime and destroy and dismantle al-Qaeda in the aftermath of the September 11 attacks . Following the invasion , members of the 23 remained in the country to provide close protection to individuals of the Secret Intelligence Service
September 11 attacks
September 11 attacks
23 Special Air Service Regiment (Reserve)