The Royal Navy's upgraded Spearfish torpedo has been declared ready for the frontline.
The weapon has been described by the Navy as the "world's most advanced torpedo".
It features a new warhead, a new, safer fuel system, a smarter electronic 'brain' and a fibre-optic guidance link with its parent submarine to improve its accuracy and lethality.
Work will now begin in turning the existing Spearfish torpedos into the new version for entry into operational service with all Royal Navy submarines by 2025.
Commodore Bob Anstey, the senior officer responsible for the programme and Deputy Director Submarines, described it as an "important milestone".
The weapon has achieved Initial Operating Capability and Cdre Anstey says the Navy remains "focused" on achieving the "ultimate aim" of Full Operating Capability.
Despite being declared operational, the torpedo has undergone three days of extensive deepwater trials on a special range in the Bahamas.
Five of the heavy torpedos were successfully fired by Astute-class nuclear-powered submarine HMS Audacious during the testing at the Atlantic Undersea Test and Evaluation Centre off Andros Island, south-west of Nassau.
Its performance at maximum operating depth was analysed and its homing abilities were challenged with the introduction of countermeasures.
The trials in the Bahamas were the latest in a string of crucial tests on the upgraded heavyweight torpedo since the decision was taken to enhance it in 2010.
The improved weapon went through its final trials off the coast of Scotland with HMS Talent earlier this year.
The Spearfish has been the Submarine Service's weapon of choice for three decades.
Cover image: Engineers on HMS Audacious prepare to fire an upgraded Spearfish torpedo at a special range in the Bahamas (Picture: Royal Navy).