Spectacular footage shows a huge Royal Navy submarine smash through metre-thick ice in the Arctic amid growing tensions with Russia.
HMS Trenchant was filmed punching through thick ice in temperatures as low as -40C as it joined to US boats on a major exercise aimed at combat in freezing water.
The drill, co-ordinated by the US Navy, came just hour after Theresa May ordered 23 Russian diplomats to be expelled from the UK following the poisoning of former spy Sergei Skripal and his daughter.
The operation was long-planned but has been keenly watched across the globe as Russia and the UK tussle over the incident that left the pair critically ill in hospital.
The 1471-tonne vessel can carry dozens of deadly missiles and has been dubbed “an impressively powerful war machine” by navy chiefs.
It will join the US war ships in a series of demanding trials in the frigid climate of the Arctic Circle, designed to test submariners' skills in operating under the Arctic ice cap.
The Ice Exercise 18 (ICEX) will see a number of simulated attacks carried out on live “targets”, the Navy said.
Commander David Burrell, the Commanding Officer of HMS Trenchant, said: "This is a tremendous opportunity to really test our skills. Working alongside the US submarines is great for us. It is like dogfighting in an ice jungle."
Defence Secretary Gavin Williamson added: "The Arctic Ocean is one of the harshest and most challenging environments on earth.
“The ability of our submarines to operate with our US allies here demonstrates the Royal Navy is always on hand and ready to defend our nation anywhere in the world from the most severe threats no matter the conditions."