An unexpected regional election victory by a previously marginal ultra-nationalist party is among a string of developments in Ukraine that threaten to fulfil the worst fears of G20 leaders as they gather for their summit in London. Lacking the protection of European Union membership, Ukraine has few of the safeguards that prevent its Western neighbours from falling into ruin. A sharply weaker currency, a collapse in exports and an economy expected to contract by at least six per cent this year has forced the country to seek £11 billion from the International Monetary Fund. Even this lifeline is endangered by...