Trump suggests he can manipulate the US dollar exchange rate, saying "it can fluctuate up and down like a yo-yo," but believes that doing so is not a good idea, and also criticizes Japan for continuously devaluing its currency. After market speculation that the US and Japan might jointly intervene in the currency market, the yen has recently appreciated by 4% over the past three trading days. In the long term, structural factors such as the Federal Reserve's independence, the expanding budget deficits, concerns over fiscal profligacy, and political polarization are exerting downward pressure on the US dollar.