Asia's central banks test Washington's leverage

TOKYO, Japan — In Tokyo, the yen has fallen to depths not seen in four decades, and the strain is now a daily reality for an export-led economy watching violent currency swings unsettle markets, households and policymakers. Against that backdrop, Washington and Tokyo have linked arms for the first joint US–Japan currency operation since 2011, a move US President Donald Trump has cast as a "signal of friendship."

Yet beneath the coordination lies an open question: who actually holds the leverage — Washington or Tokyo? US Treasury Secretary Scott Bessent plainly wants his Japanese counterpart, Finance Minister Satsuki Katayama, to treat the intervention as a privilege, even as the operation aims to confront yen bears.

The operation comes as violent yen swings threaten to detonate one of global finance's most combustible mechanisms: the yen carry trade, a strategy that has already vaporised more than a few hedge funds.

Across the Sea of Japan, another central bank is testing American assumptions in a different way. Bank of Korea Governor Shin Hyun-song ended a three-and-a-half-year rate freeze on Thursday, lifting the policy rate 25 basis points to 2.75 per cent — the BOK's first tightening move since January 2023.

The timing is more than routine. Shin appears to be picking a direct fight with the Federal Reserve's view that AI investment is not fuelling inflation. No economy is better placed to arbitrate that debate than Korea's: its open, $1.9 trillion economy has long served as an early-warning system for global inflection points, sitting on the fault lines of demand shifts between the United States, China and the high-tech export sectors AI now dominates.

The ripple effects reach well beyond the two capitals. For Japan, a successful defence of the yen would steady carry-trade markets and ease imported-cost pressures, but it also binds Tokyo more tightly to Washington's political calculus at a moment of strained global demand. For Korea, tightening while the Fed debates AI-driven price pressures signals that the world's bellwether export economies are no longer waiting for Washington to lead. Related countries, semiconductor supply chains and currency investors across the region are all exposed to the outcome.

Whether the joint yen operation holds will depend less on the size of the intervention than on the durability of the political bargain behind it; for Korea, the experiment will be read in export data, chip prices and whether the Federal Reserve eventually follows. Either way, the centre of gravity in the global monetary debate has shifted visibly towards East Asia.