Why US Joined Japan to Support Yen — And What the Rare Currency Intervention Means

Japan and the United States (US) have carried out a rare joint intervention in the foreign exchange market to support the yen, marking the first coordinated operation by the two countries to strengthen the Japanese currency since 1998.

Japan's Finance Ministry confirmed on Monday that it worked with the US Treasury to buy yen on Friday after the currency came under intense pressure from speculative selling.

The intervention followed months of discussions between officials in Tokyo and Washington, highlighting an unusually close alignment on exchange-rate policy.

Japan also made it clear it "will not hesitate to conduct further coordinated interventions in the future" if excessive volatility returns, signalling that authorities are prepared to act again if needed.

Why Did Washington Back Tokyo?

Both the countries had strong economic reasons to support the intervention. For Japan, the weaker yen has pushed up the cost of imported food and energy, adding to inflationary pressures and increasing the cost of living.

For the US, persistent yen weakness reduces the competitive impact of President Donald Trump's tariffs while volatility in Japan's government bond market risks spilling over into US Treasury markets.

How The Intervention Unfolded

Japan executed the currency operation during a period of heightened market sensitivity surrounding last week's Bank of Japan (BOJ) and US Federal Reserve policy meetings.

The move immediately strengthened the yen from around 162.80 to 157.80 against the US dollar, as per Reuters.

The US Treasury informed several banks it could participate in the operation, while a Reuters photograph showed US Treasury Secretary Scott Bessent carrying notes that included plans to buy between $5 billion and $10 billion worth of Japanese yen.

Preparations for possible US involvement began as early as January, with officials from both countries holding around 10 rounds of discussions before the intervention was eventually carried out, as per Reuters.

The yen had weakened to 163.73 against the dollar on Thursday before rebounding to 157.57 on Friday following the intervention. The currency was trading around 157.70 per dollar on Monday.

What Did Trump And Bessent Say?

Confirming Washington's participation, Bessent said, "Friday's coordinated foreign exchange actions countered disorderly yen movements."

"Treasury remains attentive and in close communication with our counterparts at MOF and BOJ. We will not hesitate to participate in further joint intervention," he added.

US President Donald Trump also acknowledged the joint action, saying, "They wanted a little bit of help, and we're always there for Japan."

"More than anything else, it was a signal of friendship," he added, referring to the US-Japan bilateral ties.

Why Has Yen Been Under Pressure?

Speculative selling has been a major driver of the yen's weakness this year, prompting Japanese authorities to step up efforts to curb excessive volatility, as per Reuters.

Broader economic factors have also weighed on the currency. Expectations that the US Federal Reserve will keep interest rates elevated have widened the yield gap between the US and Japan, encouraging investors to favour dollar-denominated assets.

Higher global energy prices following the US-Iran conflict is another factor that accelerated the yen's decline.

Will Intervention Alone Be Enough?

Currency intervention may only provide temporary relief unless it is supported by tighter monetary policy.

The BOJ raised interest rates to 1% in June, its highest level in more than three decades, but real borrowing costs remain deeply negative.

After last week's policy meeting, Governor Kazuo Ueda delivered what analysts described as the central bank's most hawkish guidance yet, strengthening market expectations of another rate hike in September, as per Reuters.

Several analysts now reportedly believe the BOJ faces growing pressure to continue normalising policy if it wants to provide lasting support to the yen.

Japan also plans to use the Federal Reserve's Foreign and International Monetary Authorities (FIMA) repo facility, enabling it to access short-term US dollar liquidity by temporarily exchanging its US Treasury holdings if required, as per a report by Moneycontrol.

According to BCA Research, the yen could remain under pressure through much of 2026 because of Japan's accommodative monetary policy. However, the research firm expects inflation to remain elevated and believes further monetary tightening by the BOJ could eventually provide more durable support to the currency.