Judging by the fact that there is only $1.3 Trillion USD in circulation I hardly think that is the truth. The intervention that was big $101 billion was the one shot and th ebig one.. but normally around japan open they openly sold a few million on the open market.. but it doesnt add up to much compared to the big intervention.
You need to remember that the majority of US dollars available are not in "hard currency/paper" form but rather is in "digital" form. You also need to remember that trillions of dollars worth of dollars are traded every day throughout the world.
Take the stock market for example, there are close to hundreds of billions of dollars worth of stocks traded on a daily basis however none of it actually has physical cash change hands.
IIRC the amount of dollars traded on forex markets is in the trillions of dollars per day, however I am having trouble finding a source on this