The yen dropped to a 33-year low against the dollar as the wide yield gap with the U.S. continued to weigh on the Japanese currency.

It closed Wednesday down 0.2% at 150.25 per dollar, the weakest since August 1990. The move increases the risk of intervention from the authorities in Tokyo, who have repeatedly said they wouldn’t rule out any options to curb against the excessive moves.

“The stakes are raised clearly,” said Bipan Rai, CIBC’s global head of foreign-exchange strategy in Toronto. “We’re now above the level for dollar-yen” in which Japan conducted its last intervention, he said.

Japan spent a record 6.3 trillion yen (about $42 billion) in October 2022 to prop up the currency as it weakened beyond the 150 level.

The yen briefly slid past 150 on Monday but recovered quickly amid weight from options-related dollar selling and suggestions of algorithmic transactions. On Oct. 3, it touched 150.16 before a sharp reversal that stoked speculation that Japan had entered the market.

“It looks like some stops are being triggered in dollar-yen to push it above Oct. 3 highs,” said Win Thin, global head of currency strategy at Brown Brothers Harriman & Co. in New York. “Thin markets aren’t helping either as the pair trade at a new high for this move.”

Officials neither confirmed nor denied whether they propped up the currency on the 3rd. The nation’s top currency official Masato Kanda has since said Japan will take appropriate steps if excessive moves are seen in currency markets; desirable that currency moves stably, reflecting fundamentals.

Meanwhile, the 10-year U.S. Treasury soared almost 14bps to 4.96% versus 0.85% for its Japanese counterpart. The gap keeps pressure on the yen.

Still, speculation the falling yen will put pressure on the Bank of Japan to adjust its monetary policy, and a potential escalation in the Middle East conflict that would boost safety demand havens, are also keeping traders cautious.

Nikkei reported over the weekend that BOJ officials were pondering the question of whether to tweak yield-curve control program as domestic long-term interest rates float higher in tandem with those in the US. It didn’t say where it obtained the information.

“Fundamentally, a program like yield-curve control is messy and there are few good options the longer you let it run,” said CIBC’s Bipan.