"Gorbachev did more than just let the colonies go. By indicating that he would not intervene he decisively undermined the only real source of political legitimacy available to the rulers of the satellite states: the promise (or threat) of military intervention from Moscow. Without that threat the local regimes were politically naked. Economically they might have struggled for a few more years, but there, too, the logic of Soviet retreat was implacable: once Moscow started charging world market prices for its exports to Comecon countries (as it did in 1990) the latter, heavily dependent on imperial subsidies, would have collapsed in any event. As this last example suggests, Gorbachev was letting Communism fall in eastern Europe in order to save it in Russia itself—just as Stalin had built the satellite regimes not for their own sake but as a security for his western frontier. Tactically Gorbachev miscalculated badly—within two years the lessons of Eastern Europe would be used against the region’s liberator on his home territory. But strategically his achievement was immense and unprecedented. No other territorial empire in recorded history ever abandoned its dominions so rapidly, with such good grace and so little bloodshed. Gorbachev cannot take direct credit for what happened in 1989—he did not plan it and only hazily grasped its long-term import. But he was the permissive and precipitating cause. It was Mr Gorbachev’s revolution."