If the world is on the brink of an out-and-out currency war, a variety of battalions has been out on manoeuvres in the past few weeks. The Bank of Japan, after six years off the battlefield, has launched a fusillade of intervention to hold down the yen in foreign exchange markets. Brazil used the guerrilla tactic of doubling taxes on capital inflows to stop the real surging. India and Thailand warned that they too might bring heavy ordnance into play.

The main combatants, the US and China, continued to exchange rhetorical salvos. Washington (and Brussels) identified undervalued currencies such as the renminbi as a prime cause of global macroeconomic imbalances. Beijing retorted that such aggression risked bringing mutual destruction upon the great economic powers.

On Monday Dominique Strauss-Kahn, managing director of the International Monetary Fund, voiced his concern. “There is clearly the idea beginning to circulate that currencies can be used as a policy weapon,” he said. “Translated into action, such an idea would represent a very serious risk to the global recovery.”