France is to boost its nuclear arsenal and extend the deterrent to cover other European countries, in a major development of its nuclear defence policy.

In a speech in Brittany, President Emmanuel Macron explained the changes as the response to an increasingly unstable strategic environment.

“The next 50 years will be an era of nuclear weapons,” he said.

Speaking to naval officers in front of a nuclear submarine at the Ile Longue base near the port of Brest, he said the number of French nuclear warheads would be increased from their current level of around 300.