"When goods cannot cross borders, armies will." The aphorism by Cordell Hull, a former US secretary of state, is one of the pithiest and most powerful rationales ever advanced for free trade. Put another way, economic integration fosters wealth creation; and wealth creation fosters security.

The axiom has served Europe well: expanded commercial links are the cement for the political building blocks that have made another war between its citizens unthinkable. It has also proved its worth in east Asia, although - or perhaps because - the region lacks Europe's common rules and mechanisms for co-operation.