It’s all about profit taking ahead of the FOMC, which sounds like a very sensible strategy to me. The USD is on its highs for the day against all other major currencies which is really an impressive performance.
Just to repeat on the order front; AUD/USD corporate bids at .9100 are stalling the fall there and solid bids are also reported in the EUR/USD between 1.3100-20, including some Asian central bank bids (although the amounts are not overly large).