The declining value of the US dollar was supposed to restore balance to global trade, discounting US exports while making imports prohibitively expensive. Yet, when the Commerce Department released November's trade data, the US trade deficit had soared to a record $60.3bn with imports up and exports down.

In truth, those numbers should not have been a surprise. Nor should they prompt a protectionist response. A large and growing share of that deficit reflects the international reach of the strongest US-based companies. Roughly one-third of the current account deficit results from US-owned subsidiaries abroad: Ford importing cars made in Mexico, for instance, or a US bank using call centres in India. These activities create value for US consumers, companies and shareholders, even if they add to the nation's trade imbalance. But they are unlikely to be responsive to even large changes in exchange rates.