Yen slides to 40-year low as U.S.-Iran strikes send oil surging

The Japanese yen slid to fresh 40-year lows on Wednesday as a renewed U.S.-Iran confrontation sent oil prices surging, delivering a double blow to a currency already weakened by months of unfavorable rate differentials. USD/JPY traded as high as 162.55 on July 8, according to Yahoo Finance data, its weakest level since 1986.finance.yahoo

Oil Shock Compounds Yen Weakness

The move was triggered by President Donald Trump's declaration that a ceasefire with Iran was "over," followed by U.S. strikes on more than 80 targets in Iran and revocation of a temporary sanctions waiver on Iranian oil, according to The New York Times and Al Jazeera. Brent crude rose as much as 3 percent on Wednesday to its highest level since June 23.aljazeera+1

The oil shock proved particularly damaging for the yen. Japan imports nearly all of its energy, so higher crude prices worsen its trade balance, while the dollar simultaneously benefits from inflation-driven expectations that the Federal Reserve will hold rates steady or raise them further. The International Monetary Fund on Wednesday downgraded its 2026 global growth forecast to 3 percent, citing the Iran war energy shock, and now expects oil prices to rise nearly 32 percent this year.apnews+1

Intervention Threat Looms

Japanese Finance Minister Satsuki Katayama has repeatedly warned that Tokyo stands ready to act. On July 3, Reuters reported that Katayama said Japan was in "regular contact with Washington on foreign exchange issues" and remained prepared to support the yen. The pair had already touched 162.84 in late June, triggering what analysts described as a record ¥11.73 trillion intervention that failed to halt the slide.matterfact+1

The yen's decline has come despite the Bank of Japan raising its policy rate to 1 percent in June. CNN reported that traders are betting the Fed will hold or even raise rates in coming months to combat inflation from the oil shock, maintaining a wide interest rate gap that funnels capital toward the dollar.mufgresearch+1

A Fragile Floor

Market participants now view the 160–163 zone as critical. Forex.com noted the pair surged toward the 162.50 area on a "sharp short squeeze rally", while MUFG Research has pushed back its forecast for the USD/JPY peak but maintains an upside target of 165. The Japan Times reported that Tokyo may be adopting a quieter intervention strategy, with the lack of clear signals keeping traders guessing.japantimes+2

The yen's weakness comes even as Japanese equities continue to rally on AI-related investment, according to Axios — a divergence that underscores how the currency's fate now rests almost entirely on energy prices and global rate expectations.axios