Page "Balance of trade" Paragraph 25

Small trade deficits are generally not considered to be harmful to either the importing or exporting economy.

However, when a national trade imbalance expands beyond prudence ( generally thought to be several percent of GDP, for several years ), adjustments tend to occur.

While unsustainable imbalances may persist for long periods ( cf, Singapore and New Zealand ’ s surpluses and deficits, respectively ), the distortions likely to be caused by large flows of wealth out of one economy and into another tend to become intolerable.