The exercise foresaw three phases.
The sonar sonar environment of the warm and shallow waters of the Middle East is particularly challenging, hence, during the first one, ships and submarines tested acoustic and non-acoustics sensor performance against known positions, gaining useful real life data for the region.
The second phase saw ships escorting HMS Illustrious as the Mission Essential Unit (MEU) along a passage whilst evading detection and simulated torpedo attacks by the American submarine.
Finally, the Los Angeles class USS Dallas tried to locate and destroy RFA Fort Austin as the MEU, in a holding box which simulated an anchorage, as the UK and US naval ships provided protection.
The exercise, saw also Merlin, Seahawk and Lynx helicopter support to the ships.
Image credit: UK MoD