I don't think that anyone has assumed that these interventions were more than firebreaks against too rapid a realignment of the dollar , but they stand to lose what little impact they've had if not enforced evenly. The series prior to the past two had been weak 100+ pip strikes that had been absorbed and returned within a few hours. These were apparently unsterilized as well ( ie. the direct purchase of dollars wasn't offset by counterpositions in alternate assets , such as bonds ) , which should have amplified their impact. The latest rounds have been coordinated, but no more effective. The threat of a prolonged coordinated intervention climate should have provided more stability than it has. Perhaps the US administration's ambivalence regarding the strong dollar , lack of eur/jpy correlation , and the generally foul odors emitted by US equity markets were compelling enough to inspire the BOJ, and most others, to accept a 115 dollar as inevitable ? For a good discussion of the mechanics of interventions check out this thread on Wilmott.com