The Japanese yen jumped nearly 1% toward 161 per dollar on Thursday before trimming its gains, rebounding from four-decade lows as traders stayed on high alert for possible currency intervention. Market participants also pointed to the US public holiday on Friday, when thinner market liquidity could amplify the impact of any official action. Finance Minister Satsuki Katayama said on Wednesday that authorities would respond appropriately to developments in the currency market at any time, reiterating earlier warnings. The yen also found some support after Federal Reserve Chair Kevin Warsh said US inflation expectations had eased over the past month, signaling there was no urgency to raise interest rates. Meanwhile, investors remain skeptical that the Bank of Japan will accelerate policy tightening as it continues its gradual normalization path, with persistent carry trades and the still-wide interest rate differential between Japan and the US continuing to weigh on the currency.