In the hours after the Supreme Court struck down one legal foundation for sweeping American tariffs, the administration simply reached for another — and the world's markets, reopening from holiday, absorbed the lesson quietly: the rules of global trade remain unwritten. The yen slipped, the dollar steadied, and from Tokyo to Brussels, governments found themselves negotiating not with a fixed policy but with a moving target. It is a moment that reveals how deeply the architecture of international commerce depends not just on law, but on the expectation that law will hold.
Yen weakens as tariff uncertainty roils Asian markets post-holiday
Back in a very uncertain environment, just when countries thought they were signing deals
Mark
So the Supreme Court told Trump he couldn't use that 1977 law for tariffs, and then he just... used a different law instead?
Mimi
Exactly. Within hours. So the court's ruling didn't actually stop the tariffs—it just forced him to find another legal hook. And that's what spooked the markets.
Luke
But we should be clear: the court did rule his original move exceeded his authority. That's a real constraint, even if he found a workaround. The question now is whether this new law holds up.
Mark
And the yen weakened because of all this?
Mimi
Partly. But also because China announced export controls on Japanese companies at the same time. So Japan got hit from two directions—U.S. tariff uncertainty and souring relations with China.
Luke
Though the yen only moved 0.3%. That's not huge. The real story might be that markets are numb to this now, or that they're waiting to see what actually happens rather than reacting to threats.
Mark
What about the currency intervention the Nikkei reported?
Mimi
U.S. authorities apparently conducted rate checks last month to support the yen, without Tokyo formally asking. The report suggested Japanese officials might be okay with a weaker yen now.
Luke
But that's one report from one newspaper. We don't have confirmation from the Japanese government or the Fed on what exactly happened or why. It's worth noting that as an interpretation, not a fact.
Mark
So where does this leave global trade?
Mimi
In limbo. The EU postponed its trade deal vote with the U.S. Japan asked for favorable treatment. China's yuan actually strengthened because traders think Chinese exports might benefit. Everyone's waiting to see what Trump does next.
Luke
And the Fed's holding rates steady through June, which adds another layer of uncertainty. You've got monetary policy uncertainty, trade policy uncertainty, and geopolitical tensions all at once.
Mark
Is there any clarity coming?
Mimi
Not soon. Trump's already signaled more tariffs are possible. The administration is considering new national security levies on key industries. This is a moving target.
Il Polso
- The Supreme Court blocked Trump's tariff authority on Friday — and by Monday he had invoked a different law and raised levies to 15% on all U.S. imports, signaling that legal setbacks would not slow the trade offensive.
- China escalated separately, announcing export restrictions on 20 Japanese entities over what it called Tokyo's 'remilitarisation,' adding a bilateral pressure point that weighed directly on the yen.
- Japan's trade minister scrambled to secure favorable treatment from Washington, while the European Parliament quietly postponed its trade deal vote with the U.S., unwilling to ratify an agreement whose terms could shift overnight.
- The yen fell 0.3% to 155.05 per dollar — a modest move that masked deeper anxiety, as currency strategists noted Japanese officials may now be more tolerant of yen weakness than markets had assumed.
- Beyond trade, the Fed signaled rates would hold through at least June, AI investment confidence wavered, and U.S. diplomatic personnel were withdrawn from Beirut — a confluence of pressures leaving global markets searching for stable ground.
In the hours after the Supreme Court struck down one legal foundation for sweeping American tariffs, the administration simply reached for another — and the world's markets, reopening from holiday, absorbed the lesson quietly: the rules of global trade remain unwritten. The yen slipped, the dollar steadied, and from Tokyo to Brussels, governments found themselves negotiating not with a fixed policy but with a moving target. It is a moment that reveals how deeply the architecture of international commerce depends not just on law, but on the expectation that law will hold.
Markets across Asia reopened Tuesday to a familiar kind of disorder. The Supreme Court had ruled Friday that Trump lacked authority to impose tariffs under the emergency law he had invoked — but within hours, he reached for a different statute and imposed new levies anyway. By the time exchanges came back online, the message was plain: the tariff fight was not over, and no one could say what the rules would be tomorrow.
The yen weakened 0.3% to 155.05 per dollar as traders absorbed the fresh uncertainty. The dollar index edged up 0.12%, while the euro and sterling barely moved. These were not dramatic swings — they were something quieter: a market trying to price an unknowable future. Ray Attrill of National Australia Bank put it plainly: the world had returned to a very uncertain environment at the precise moment most countries thought they were finally moving forward.
Trump sharpened that uncertainty over the weekend, raising the temporary tariff ceiling to 15% and warning on social media that countries 'playing games' would face even higher duties. Behind the scenes, the administration was reportedly weighing new national security tariffs on batteries, industrial chemicals, and telecom equipment. The European Parliament, watching all of this, postponed its trade deal vote with the United States.
Japan and China, both returning from holidays, found themselves caught in the crossfire. Tokyo's trade minister asked Washington not to treat Japan less favorably than last year's agreements had allowed. Beijing, meanwhile, announced export restrictions on 20 Japanese entities, citing Japan's 'remilitarisation' — a move that signaled deteriorating bilateral relations and added further pressure on the yen. A Nikkei report suggesting U.S. authorities had been open to joint currency intervention last month complicated the picture further, with some strategists reading it as a sign Japanese officials were more tolerant of yen weakness than previously assumed.
Elsewhere, the Federal Reserve signaled it would hold rates steady at least through June, confidence in AI investment was showing early cracks, and the State Department began withdrawing non-essential embassy staff from Beirut. The picture that emerged was of a global financial system searching for footing in an environment where the rules kept changing — and no one could say with certainty what came next.
Markets across Asia woke to a familiar kind of chaos on Tuesday: the yen sliding, the dollar climbing back, and the entire architecture of global trade suddenly uncertain again. The trigger was straightforward enough—the Supreme Court had ruled on Friday that Donald Trump lacked the authority to impose tariffs under a 1977 emergency law he'd invoked. But Trump, within hours, simply reached for a different law and imposed new levies anyway. By the time Asian exchanges reopened after their holidays, the message was clear: the tariff fight was far from over, and no one knew what the rules would be tomorrow.
The yen weakened 0.3% to 155.05 per dollar as traders absorbed the fresh uncertainty. The dollar index, measuring the greenback against a basket of major currencies, rose 0.12% to 97.81. The euro barely moved, down just 0.04% to $1.1779, while sterling held steady at $1.3486. These were not dramatic swings, but they reflected something deeper: a market trying to price an unknowable future. Ray Attrill, head of currency strategy at National Australia Bank, captured the mood plainly: the world had just returned to "a very uncertain environment" at the precise moment when most countries thought they were finally signing trade deals and moving forward.
Trump's next moves sharpened that uncertainty. On Saturday, he announced he would raise a temporary tariff from 10% to 15% on all U.S. imports—the maximum allowed under the law he'd just invoked. On Monday, he took to social media to warn that countries "playing games" in response to the Supreme Court ruling would face even higher duties. Behind the scenes, the Trump administration was considering new national security tariffs on batteries, cast iron, plastic piping, industrial chemicals, and power grid and telecom equipment, according to reporting from the Wall Street Journal. The European Parliament, watching this unfold, postponed a vote on its trade deal with the United States.
Japan and China, reopening after their own holidays, found themselves caught in the crossfire. Japan's trade minister, Ryosei Akazawa, spoke with U.S. Commerce Secretary Howard Lutnick on Monday and asked that Tokyo not be treated less favorably than it had been under last year's agreement. China, meanwhile, announced export restrictions on 20 Japanese entities, citing what it called Tokyo's "remilitarisation." The move was a signal of deteriorating relations between the two countries, and it weighed on the yen. Japanese Prime Minister Sanae Takaichi told parliament that a weak currency had both advantages and disadvantages—a careful statement that followed a Nikkei report suggesting U.S. authorities had been willing to conduct joint currency market intervention to support the yen last month. Carol Kong, a currency strategist at Commonwealth Bank of Australia, noted that markets had interpreted this report as showing Japanese officials were more tolerant of yen weakness than previously thought.
The tariff turbulence was not the only thing roiling markets. Doubts were creeping in about the sustainability of massive artificial intelligence investments. The Federal Reserve was signaling it would hold interest rates steady at least through June, with Fed Governor Christopher Waller saying on Monday he would be open to keeping rates unchanged at the March meeting if February jobs data showed the labor market had "pivoted to a more solid footing" after a weak 2025. Geopolitical tensions were also rising: the State Department announced it was pulling non-essential personnel and their families from the U.S. embassy in Beirut amid growing concerns about potential military conflict with Iran.
In the broader currency market, the Australian dollar strengthened 0.2% against the greenback to $0.7066, while New Zealand's kiwi was essentially flat at $0.5962. China's yuan, by contrast, hit its strongest level against the dollar in nearly three years on hopes that Trump's new tariff regime would lower taxes on Chinese exports. Cryptocurrencies fell: bitcoin dropped 2.1% to $63,214.65, and ether declined 1.9% to $1,827.81. The picture emerging was one of a global financial system trying to find its footing in an environment where the rules kept changing and no one could say with certainty what came next.
Citazioni salienti
Now we're back in a very uncertain environment, just at a point where most countries had signed or were on the cusp of signing trade deals.— Ray Attrill, head of currency strategy at National Australia Bank
Markets interpreted the report as suggesting Japanese authorities have a greater tolerance for JPY weakness.— Carol Kong, currency strategist at Commonwealth Bank of Australia
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Economy & Finance