HMS Vanguard and Le Triomphant submarine collision

[1][2] Le Triomphant was returning from a tour of duty when the incident occurred; it was carrying a crew of 111, and capable of being equipped with 16 M45 ballistic missiles, with a standard patrol load of 48 warheads.

[5] On 16 February 2009, the incident was confirmed[1] by First Sea Lord Sir Jonathon Band, in response to a question at an unrelated event.

Ballistic missile submarines are designed to conceal themselves while on patrol, and the use of active sonar would immediately reveal the boat's position.

[1] Several media outlets have referred to comments by retired Royal Navy Commodore Stephen Saunders, editor of Janes Fighting Ships, where he described the incident as "very serious" and said it was time for France and Britain to coordinate their submarine operations more actively, suggesting that the use of operating areas is not communicated between France, the UK and the United States or that communication procedures were not effective.

In a commentary article for The Independent newspaper, he said that whilst it is not known whether the UK and France exchange information now, it was not the case when he served as Flag Officer Submarines in 1984.

He recalls that his French counterpart proposed that London and Paris share information on SSBN patrols, precisely to avoid an incident at sea, but no agreement was reached at the time on achieving that.

[16] Hervé Morin, France's Minister of Defence, said that they "face an extremely simple technological problem, which is that these submarines are not detectable".