AFTER RUSSIA’S annexation of Crimea in 2014 Europe feared that Vladimir Putin would cut supplies of piped gas passing through Ukraine to European customers. That worry led Poland’s then prime minister, Donald Tusk, to issue a stark warning: “Excessive dependence on Russian energy makes Europe weak.” As a full-scale invasion of Ukraine by Mr Putin’s forces unfolds, Europe looks, if anything, weaker. Despite some efforts to diversify…