Can currency interventions be effective?

There is a question whether the US Treasury will carry out currency interventions to weaken the dollar, and also whether these interventions can be effective : If the purpose is to weaken the dollar; the US Treasury therefore has no need to hold foreign currency reserves since it will sell dollars, which it can do in unlimited quantities by issuing dollar-denominated debt (foreign currency reserves are necessary when a central bank wants to sell foreign currencies to weaken its currency); the size of the interventions is therefore no problem; Available research studies show that currency interventions (we will here use this term in the sense of interventions aimed at obtaining a depreciation of the exchange rate) are far more effective when they are accompanied by money creation (this is the case if the central bank creates money to buy foreign currency bonds). But in the United States, this would involve currency interventions by the Treasury that would be accompanied by money creation (unless the Federal Reserve resumed quantitative easing in parallel). It is then what is called "sterilised" currency interventions, where purchases of foreign currency bonds are not accompanied by money creation, and this type of intervention does not seem very effective in changing the exchange rate. Federal Reserve cooperation would be needed for currency interventions to be effective in the United States.