The Captain Faslane Flotilla (CAPFASFLOT) is responsible to the Commander-in-Chief Fleet (CINCFLEET) for ensuring that Flotilla units achieve the required state of operational readiness and availability to enable operational deployment.

The Flotilla comprises two Squadrons of submarines and ships which are base ported and maintained at HM Naval Base Clyde.  The First Submarine Squadron (SM1) consists of the UK’s Strategic Deterrent Force of four Vanguard Class submarines (SSBNs) and the Swiftsure Class attack submarine, HMS Sceptre. HMS Astute, the first of the Royal Navy's new class of SSNs, arrived at HM Naval Base Clyde in late 2009 and will be joined in the Flotilla by her sister ships over the next few years.. 

The First Mine Countermeasures Squadron (MCM1) comprises of seven Sandown Class mine warfare vessels and a deployable MCM Battlestaff.

The SSBN force is given the task of maintaining the UK’s continuous at sea deterrent.  Ships and submarines can be expected to operate anywhere in the world in a variety of roles, from conducting major national and multi-national operations as part of a task group, to independent patrols such as enforcing sanctions, intelligence gathering or providing humanitarian relief.