Alastair Cooke has been a journalist for around 70 years, so he's seen trade wars come and go. On the BBC site right now he reflects on the Smoot-Hawley bill -- which put a big tariff on imports to the US in an attempt to cure the economic gloom that had persisted since the Wall Street crash.

Hoover signed the bill, the market went down, unemployment went up, and the Europeans were furious. They retorted in kind. US unemployment shot up to 13 million, and an economic problem had turned into the Great Depression.

And now President Bush has slapped 20% on imported steel, unleashing predictable outcries from Japan, Europe and Russia. And now the EU and others are threatening retaliation.

Tariffs might look good for domestic consumption, but trade wars, ultimately, don't benefit anyone - even the industries you're trying to help.