US Commerce Secretary Wilbur Ross defended those tariffs and warned Washington would be prepared to fight back in future against countries it felt had flouted the rules.
The dollar’s sell-off was also helped by investors betting on tighter monetary policies by major central banks, bringing them in line with the Federal Reserve.
The dollar took a hit from the developments and in Asia extended the losses, briefly falling below 109 yen for the first time since September 2015 before edging back up.
That hit Japan’s benchmark Nikkei 225, which ended the morning 0.9 per cent lower, having fallen 0.8 per cent on Wednesday from a 26-year high.
Stephen Innes, head of Asia-Pacific trading at Oanda, said: “While we already knew the administration previously favoured a weaker dollar, his comments caught the dollar prone and defenceless, opening floodgates to a massive wave of dollar-selling.”