Britain has deployed a nuclear submarine under the Arctic for the first time in a decade amid growing tension with Russia over its military build-up there.

HMS Trenchant has joined two American vessels for an exercise that will include improving war-fighting capabilities in extreme cold water.

The submarine carries Tomahawk cruise missiles and Spearfish heavyweight torpedoes and is powered by a Rolls Royce nuclear reactor.

The drill was long-planned but has taken on extra significance after the attack on the former double agent Sergei Skripal and his daughter in Salisbury.

Gavin Williamson, the Defence Secretary, said “The Arctic Ocean is one of the most unique and harshest environments on earth.

“The ability of our submarines to operate with our US allies here demonstrates how the Royal Navy is always on hand and ready to defend our nation anywhere in the world.”