Trump signals Iran de-escalation and US-Japan currency intervention move markets

What happened Monday

Global markets moved on two fronts tied to the Trump administration. First, President Trump said he would order U.S. forces to hold off on further attacks against Iran and that a deal to end the fighting was close, a reversal from just a day earlier when he said he was “losing faith” in negotiations and warned the U.S. military “will be hitting them very hard.” The comments sent oil prices sharply lower and lifted U.S. stock futures: S&P 500 futures rose 0.6%, Dow futures climbed 1.1%, and Nasdaq futures gained 0.3% ahead of the opening bell. Brent crude fell $4.27 (4.9%) to $83.66 a barrel, and U.S. benchmark crude dropped $4.86 (5.8%) to $79.81. It was the latest swing in oil prices that have whipsawed since the U.S. and Israel struck Iran in late February, largely tracking Trump’s shifting rhetoric on the conflict.

Second, the U.S. Treasury, through the Federal Reserve Bank of New York, bought billions of dollars’ worth of Japanese yen alongside Japan’s government — the first time in roughly 30 years Washington has intervened to prop up the currency. The move followed a cabinet meeting where Treasury Secretary Scott Bessent was photographed holding a note reading “To Do. Buy Japanese Yen (JPY) $5-10 bil.” The dollar, which had climbed to 40-year highs against the yen (trading near 164 yen last week), fell to 155.20 yen in early Tokyo trading Monday before settling at 156.79 by day’s end. Trump called the intervention “good for the world economy” and quipped that “Japan’s been very good to us, with the exception, of course, of Pearl Harbor.”

How markets reacted across Asia

Japan’s Nikkei 225 fell 0.9% to 63,754.90. South Korea’s Kospi dropped 5.1% to 6,257.45, a sharp reversal after soaring 17.9% Friday in its best single-day performance ever, driven by Samsung Electronics and SK Hynix shares each jumping more than 25%; both stocks gave back 8.8% on Monday. Hong Kong’s Hang Seng rose 0.5% to 26,009.40, while Shanghai’s Composite slipped 0.6% to 3,809.66.

Why Japan’s currency needed propping up

Japan has been fighting an accelerating yen decline that has strained its economy, which depends heavily on imported energy and food. A weaker yen makes those imports pricier, fueling inflation just as Prime Minister Sanae Takaichi faces political pressure to control prices and revive growth. Japan has spent billions since 2022 trying to slow the yen’s fall without success. Contributing factors include the Bank of Japan’s ultra-low interest rates, which make the currency less attractive to investors, and government debt exceeding 200% of GDP, the highest in the G20. The war-driven disruption to Middle East oil and gas exports has compounded the problem, pushing Japan to spend billions more on fuel subsidies to cushion consumers.

How the coverage differs

Fortune frames the story primarily as a markets-and-oil dispatch, centering on the Iran de-escalation as the catalyst for stock and oil moves, with the yen intervention treated as a secondary, related development. The Guardian instead makes the currency intervention the main story, using an explainer format to unpack Japan’s underlying economic troubles — debt, low interest rates, inflation — and to raise pointed questions about Washington’s motives, including the theory that Japan’s yen-buying (funded by selling U.S. Treasury bonds) could raise U.S. borrowing costs. Fortune includes an analyst quote from Stephen Innes describing the intervention as Washington moving from merely tolerating Japan’s currency defense to actively joining it. The Guardian, by contrast, highlights Trump’s own joking remark about Pearl Harbor and details the Bessent “To Do” note as the first visible signal of the coordinated action.

Why this matters

The dual story illustrates how geopolitical signaling and currency policy can ripple through global markets almost instantly. Trump’s on-and-off statements about Iran have repeatedly driven oil price swings since fighting began in late February, underscoring how much energy markets are hostage to a single leader’s public comments. Meanwhile, the yen intervention marks a rare and historically significant move — the first joint U.S.-Japan currency defense in about three decades — with implications beyond Tokyo. Because Japan financed part of its yen purchases by selling U.S. Treasury bonds, the maneuver could push up U.S. borrowing costs, tying America’s own fiscal position to its ally’s currency troubles. Both threads reflect a broader pattern: markets reacting in real time to shifting signals from Washington, whether on war or currency policy.

Sources

• Fortune
• The Guardian Business

Featured photo: Sergey Galyonkin via Wikimedia Commons (CC BY-SA 2.0)