A DESPERATE ATTEMPT TO EVADE WARNINGSJapan has a long history of intervening in currency markets, sometimes to prevent the yen’s rapid appreciation and sometimes, as is the case now, to limit its depreciation. The US Treasury’s involvement is the new wild card.Is there logic to coordinated intervention? Currency markets have a tendency to overshoot in one direction or the other when circumstances change. Smoothing out such volatility is a legitimate reason for intervention.Adding the Treasury’s firepower will surely scare off speculators trying to profit off unwarranted volatility in the yen. But such interventions invariably fail to stem the tide when…