To whom...,
I need an answer to this question and I'm sure there is one I don't know about. Why, I wonder, have the smaller countries not engaged in so-called "front-running," i.e., trading in advance of their own knowledge of future interventions. Thus, if I am a finance minister trying to defend the Brazilian real, I first call several brokers and, with public funds, go long the real, then I order an intervention. Obviously there will be squawking but so what? I'm the finance minister of a sovereign nation trying to defend my currency. The defense is obvious: smaller countries are simply competing with speculators who have more money than their little countries can muster. So, you do what needs to be done to level that playing field.
It may be that countries already do this, or there is some reason why it's not possible, but I don't know what it is.
peace