Question to the Ministry of Defence:
To ask the Secretary of State for Defence, what recent comparative assessment he has made of the viability of maintaining the continuous at-sea nuclear deterrent with a (a) three and (b) four submarine nuclear weapons fleet.
The United Kingdom's nuclear deterrence posture is continually reviewed to ensure we can meet the current security threats. Continuous At Sea Deterrence requires four nuclear-armed submarines to ensure at least one is on patrol at all times, taking account of the cycle of deployment, training, and routine and unplanned maintenance. Three submarines cannot deliver an assured deterrent against current policy.