The USS Connecticut and USS Hartford, two nuclear-powered attack submarines, and the HMS Trenchant, a Trafalgar class sub, carried out several arctic transits, North Pole surfacing, and collected data for scientific purposes, the UK Defence Journal noted.
"The ability of our submarines to operate with our US allies here demonstrates the Royal Navy is always here on hand and ready to defend our nation anywhere in the world from the most severe threats no matter the conditions," UK Defence Secretary Gavi Williamson
said March 15.
The exercise, dubbed ICEX, lasted five weeks.
Meanwhile, US land forces have been going through a training exercise in Arctic conditions in Alaska as part of the Arctic Edge 2018 exercises.
"It's a chance for us to get up here in these extreme conditions and conduct training to make sure the equipment is working, and we are keeping those skill sets sharp," said the director of operations, joint special operations task force, Alaska.
While the weather was frigid, "the views are spectacular," North American Aerospace Defense Command (NORAD) and Northern Command said Wednesday.
About 1,500 US personnel from across the military participated in Arctic Edge 2018, according to the military.