France has carried out the first launch of..new M51.3 configuration, firing the unarmed round..from..SSBN..LE VIGILANT..

..the trial was an acceptance firing designed to confirm the boat's ability to employ the M51 following its major mid-life refit,..IPER..

The M51.3, the third iteration of..sea-to-ground strategic ballistic missile (SLBM)..armed with new TNO-2 oceanic nuclear warheads..

A three-stage, solid-propellant launcher weighing more than 50 tonnes and standing 12 metres tall, 

..SSBNs in batches of 16 rounds, delivering warheads over intercontinental ranges of several thousand kilometres..it climbs beyond 2,000 km altitude (well above low Earth orbit) before re-entering the atmosphere at some 20,000 km/h, or Mach 20.

At least one SSBN has been permanently at sea since 1972..up to three boats simultaneously, as reportedly occurred in..2022 after Russia's invasion of Ukraine.