HMS Agamemnon, Britain’s sixth Astute-class nuclear-powered attack submarine, has left BAE Systems’ shipyard in Barrow-in-Furness after 13 years under construction. The £1.65 billion vessel is beginning sea trials, marking progress towards entering Royal Navy service and strengthening the UK’s contribution to NATO and maritime security.

The 7,400-tonne, 97-metre submarine has a crew of about 100 and was originally expected to be operational by 2022. It will join five other Astute-class submarines, although the article says those vessels were awaiting maintenance at the time, raising concerns about the Navy’s available attack-submarine capacity and its ability to protect critical infrastructure and support the UK’s nuclear deterrent.