The surprise proposal, which came during a ministerial meeting in Brussels, shows how keen French president Emmanuel Macron is to continue close security links with Britain. However, some critics have condemned it as an attempt to drive a wedge between Britain and US-led Nato. Sources confirmed that the offer was discussed again at a Whitehall briefing last month, as officials mulled over a speech by Macron in which he discussed creating a European nuclear deterrent which does not rely on the US.
Britain’s four nuclear-powered ballistic missile submarines are coming to the end of their life and are due to be replaced by new Dreadnought-class Trident carriers over the next 10 years.
Yesterday Royal Navy sources reiterated there was “absolutely no reason to suggest” that replacing the submarine fleet would lead to capability gaps.
France operates four submarines to deliver its “Continuous At Sea” nuclear deterrent, as well as two squadrons of nuclear missile carrying Mirage 2000N and Rafale attack aircraft.
Though part of Nato, it does not extend its nuclear umbrella to members.
It is the 40-strong Rafael squadron which may, in part, be placed at Britain’s disposal in the “unlikely event” of a submarine shortage.
In November, France and Britain will celebrate the 10th anniversary of the Lancaster House mutual defence treaties.
Under the terms of the treaty both countries are already co-operating in various ways to manage their nuclear stockpile.
Jean-Pierre Maulny, of the French Institute for International and Strategic Affairs, said the offer to assist Britain was “consistent” with French policy.
Last week it emerged the US had agreed to share the technology behind its new W93 sea-launched nuclear warhead with Britain as a Trident replacement.