When a government can spray round a trillion dollars on more or less what it pleases, everything gets political real fast. Last week, 53 members of Congress signed a letter urging that US dollars be “used to create American jobs in America – not Chinese jobs in China”. They want the proposed US stimulus package to be spent only on US-sourced materials, equipment and software.

It is not just US politicians that are waving the flag. Spanish leaders want their public to buy local as well. Some tariffs are also being raised in countries such as Russia and India. Yet governments everywhere need to take care. Protectionism stymies growth, as even nutty nationalists must know. It also has the potential to backfire politically.