The yen fell on Wednesday to its weakest levels against the dollar since 1990, with markets alert to any signs of intervention from the Japanese authorities to prop up their currency.
The dollar reached as high as 155.17 yen, its strongest since 1990, before falling back in choppy trading, a sign of market nervousness around the 155 level. It was last at 154.97, up 0.09%.
The decline in the yen comes after a string of strong US inflation data pushed the dollar to five-month highs and reinforced expectations that the Federal Reserve is unlikely to be in a rush to cut interest rates this year.
The yen's slide against the dollar has revived anticipation of currency intervention. Japanese Finance Minister Shunichi Suzuki and other policymakers have said they are watching currency moves closely and will respond as needed.
The strong dollar prevailed at last week's International Monetary Fund/World Bank Spring meetings in Washington too, and the United States, Japan and South Korea issued a rare joint statement on the issue.
Speaking after the Group of 20 (G20) finance leaders' meeting in Washington, Bank of Japan Governor Kazuo Ueda said the Japanese central bank may raise interest rates again if the yen's declines significantly push up inflation, highlighting the dilemma the weak currency has become for policymakers.
The Bank of Japan concludes its latest policy meeting on Friday.