HMS Trenchant Ice Smash

Because of the potential for oil, the arctic may well become a bone of contention for opposing factions. This probably is the reason for a major exercise in which nuclear powered hunter/killer submarine HMS Trenchant smashed through a metre of ice in the Arctic Ocean.

You don't have to agree with the politics or strategy to be impressed by the tech it takes to do this.

I wonder If the Canadian military asked the Brits to do this as a counter to both the US and Russia. Being that we don't have a sub capable of patroling the arctic.

It was part of an exercise with the US Navy. But I've no doubt that the current arctic bone of contention with Russia(they are trying to claim large swathes of it) is behind it.

From 2007: BBC NEWS | World | Europe | Russia plants flag under N Pole

I don't think it takes that much tech to break 1m of ice, a submarines buoyancy pressure probably far outweighs the material breaking stresses of a sheet of 1m of ice. especially when you consider the size of the sub and so on.
militaries the world over consistently try to make out that their technology is superior to others, which is why there are so many military air shows, parades, demonstrations ect.
If a military exercise had any real relevance strategically you would not know about it until well after the fact.
Kind of like how the annexation of Crimea went down. That was a military op, an actual one, 90% of stuff you see in the media is political posturing.
If and when major powers go to war again, we will have new weapons appearing out of the woodwork, new tech, stuff we had no idea existed.
well at least from china and russia, america... I think they have forgotten to keep your secrets to your self in terms of military hardware.

As you can see from here, 10 inches of ice is enough to support 8 tons.
Ice Thickness and Strength for Various Loads

This nuclear powered ship uses 21500kw of power to break through at a speed of 2 knots. It has to repeatedly back up and ram the ice until it breaks - and this is what it was designed to do - whereas a submarine isn't specifically designed to break through ice alone.
Breaking the ice: opening up the Arctic ocean