On Wednesday, over tea and cakes with veterans of the Ukraine war, President Vladimir Putin announced Russia had tested a new weapon. "There is nothing like this," the Russian leader said of the Poseidon - a nuclear-powered, nuclear-capable underwater drone that can be fired like a torpedo and which a senior Russian MP said could "put entire states out of operation". When it was first unveiled in 2018, Russian media said the Poseidon would be able to achieve a speed of 200km/h (120mph) and