Japan ramped up its warnings against currency speculation Friday after the yen slid to a five-month low following a hint from the central bank chief that he may wait longer than expected before raising interest rates.

“The government is deeply concerned about recent currency moves, including those driven by speculators,” Finance Minister Katsunobu Kato said on Friday. “We will take appropriate action if there are excessive moves in the currency market.”

The yen regained some ground against the dollar after Kato’s remarks, strengthening to as much as ¥156.89 after earlier weakening to as much as ¥157.93. The Japanese currency strengthened a little further after currency chief Atsushi Mimura also backed up Kato with similar comments in the afternoon.

“We’re deeply concerned about recent foreign exchange moves,” Mimura told reporters. “For now I think it’s best not to say more beyond saying we’ll take appropriate responses against any excessive moves.”

The senior officials’ comments come as recent sharp movements in the yen feed into concerns that the government may intervene in the currency market. Authorities have stayed out of the market since July, when the yen hit ¥160 against the dollar, partly driven by speculators capitalizing on the wide interest rate gap between Japan and the United States. Tokyo has spent close to $100 billion propping up the yen so far this year.

With the holiday season approaching, liquidity in the market will decline raising the possibility of more abrupt moves in the currency. Low liquidity also presents policymakers in Japan with a potential opportunity to have a relatively larger impact on the currency level if they do step into the market.

The yen experienced a sharp slide Thursday following Bank of Japan Gov. Kazuo Ueda’s comments hinting at the possibility of waiting longer before its next rate hike. The central bank kept rates unchanged at the end of its meeting on Thursday, as expected by just over half of the economists surveyed by Bloomberg. Most respondents had projected the next rate hike to come by January.

Currency chief Mimura refrained from commenting on the BOJ’s recent communication, saying he should respect the central bank’s independence.

Overnight revisions to U.S. gross domestic product data and the Federal Reserve’s preferred inflation gauges put further pressure on the yen, as it strengthened the market’s view that the Fed might slow its easing measures further. This followed a reduction in the number of the Fed’s expected rate cuts in 2025.