The Awesome Aggie is British!
From https://www.forcesnews.com/services/navy/awesome-aggie-newest-nuclear-powered-submarine-completes-first-dive-ahead-joining
From https://www.forcesnews.com/services/navy/awesome-aggie-newest-nuclear-powered-submarine-completes-first-dive-ahead-joining
Quote:
The Royal Navy's newest Astute-class submarine has completed her first underwater trial at BAE Systems in Barrow-in-Furness, under the control of her Royal Navy crew.
HMS Agamemnon nicknamed Awesome Aggie the sixth of the Astute-class submarines, submerged for a three-day trim dive to test her stability, watertight integrity and buoyancy.
It forms a critical stage in testing the 7,400-tonne, 97-metre vessel, which was recently commissioned into the Royal Navy by His Majesty King Charles III, before she enters full operational service.