To ask the Secretary of State for Defence, when the Mk4A upgrade is planned to come into service.
17 June 2016
The UK currently fields the Trident Mk4 warhead as part of the Trident Strategic Weapons System. In order to ensure continuity of the Mk4-based capability, the Mk4A Arming, Fuzing and Firing system is a non-nuclear component being introduced into the UK Trident warhead to replace a similar component. The Mk4A programme will not increase the destructive power of the warhead.
Approval to procure the new Arming, Firing and Fuzing mechanisms, to manage obsolescence in Mk4 and to adopt a Mk4A component was given in January 2006. I am withholding further details of the date of the Mk4A component's entry into service, the cost of the Mk4A programme and the extension in operational life expected for the purposes of safeguarding national security.