The United States has deployed two nuclear-powered submarines to help protect critical transatlantic undersea cables from potential Russian sabotage, according to military sources, amid mounting warnings that Vladimir Putin could be preparing to strike targets in Europe. The move matters because these cables, particularly vulnerable at the GIUK gap between Greenland, Iceland and Britain, carry the vast majority of transatlantic data and financial transactions, and Britain's own naval forces are said to lack the capacity to safeguard them alone. Warnings from Polish PM Donald Tusk and French President Emmanuel Macron about intensifying Russian threats against Nato states add to the sense of urgency behind the deployment.

Cables between Britain and the US handle more than 90 per cent of the UK's international banking transactions, underscoring the economic stakes. The First Sea Lord, General Sir Gwyn Jenkins, stressed the strategic importance of the Atlantic in protecting undersea infrastructure, while Nato is separately drawing up contingency plans, with US and French naval support, to counter any Russian move against Svalbard, a Norwegian Arctic archipelago whose sovereignty Moscow disputes. Intelligence and defence sources suggest the High North, rather than Eastern Europe, could be the real flashpoint, warning that melting Arctic ice is reshaping the region's strategic significance and that Russia is already testing Nato's defences and mapping undersea cables there.