The US has been the main culprit behind the destabilising global imbalances of recent years. America’s massive current account deficit absorbs about 75 per cent of the world’s surplus saving. Most believe that a weaker US dollar is the best cure for these imbalances. Yet a broad measure of the US dollar has dropped 23 per cent since February 2002 in real terms, with only minimal impact on America’s gaping external imbalance. Dollar bears argue that more currency depreciation is needed. Protectionists insist that China – which has the largest bilateral trade imbalance with the US – should bear a disproportionate share of the next downleg in the US dollar.

There is good reason to doubt this view. America’s current account deficit is due more to bubbles in asset prices than to a misaligned dollar. A resolution will require more of a correction in asset prices than a further depreciation of the dollar. At the core of the problem is one of the most insidious characteristics of an asset-dependent economy – a chronic shortfall in domestic saving. With America’s net national saving averaging a mere 1.4 per cent of national income over the past five years, the US has had to import surplus saving from abroad to keep growing. That means it must run massive current account and trade deficits to attract the foreign capital.