Further evidence of the shift in global power, or just noise? China overtook the US to become Japan’s biggest trading partner in the fiscal year just ended. American consumers, once stalwart buyers of Japanese gadgets and other goods, appear to be losing momentum: exports bound for the US rose just 2 per cent last month on a year-on-year basis, while those headed to China increased by 15 per cent.

Yet the US can probably rest assured that it is not yet being usurped by China. Much of what China buys are parts and materials for processing or assembly: official customs statistics suggest only about half of all imports stay in the country. That is probably as true for Japanese goods – consumer electronics manufacturers and carmakers all run plants in China – as for any others. Nor need Japan’s March surplus with China, the first in three years, raise too many alarm bells, since the new year holiday caused distortions.

Nonetheless, burgeoning Asian middle classes mean intra-regional trade carries more clout – and for exporting companies theoretically introduces more currency risk. For now, exchange rates are in Japan’s favour: the renminbi shadows the US dollar, and other Asian currencies are strengthening. Thus the yen has fallen 9 per cent against the Korean won since the beginning of 2006 and 12 per cent against the Malaysian dollar. That helps the economy – Barclays Capital estimates growth in net exports will add 0.3-0.4 percentage points to first-quarter gross domestic product. Corporate earnings also get the added boost of foreign exchange gains. A stronger yen would reverse the latter, and crimp some demand. Regardless of what the Detroit lobby believes, however, it would not hugely undermine competitiveness in key sectors. In some ways at least, the structural dynamics of trade are as entrenched as ever.

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