The U.S. and Japan's recent joint intervention to prop up the yen was not entirely unprecedented, but the tactics employed signaled a deeper unease about the dollar's preeminent role in global finance, according to a prominent currency expert. In a Tuesday op-ed for the Financial Times, Barry Eichengreen, an economist at the University of California at Berkeley, dissected the maneuver, which he said reflected mounting anxiety over rising long-term yields. On the American side, the Federal Reserve Bank of New York opted to sell euros rather than dollar-denominated assets to purchase yen. Eichengreen noted that this approach allowed the U.S. to avoid adding to the pressure on the Treasury market, which is already grappling with a flood of new debt issuance. The federal government must finance a $2 trillion budget deficit this fiscal year, and it is competing with AI hyperscalers that are also selling large volumes of their own bonds. This torrent of public and private debt, combined with fierce competition for investor demand, has pushed yields higher, driving up interest costs and widening the deficit. Meanwhile, Japan, the world's largest holder of U.S. debt, refrained from selling Treasuries and instead tapped the Federal Reserve's Foreign and International Monetary Authorities (FIMA) Repo Facility. This relatively obscure tool allowed Tokyo to borrow dollars against its existing Treasury holdings, securing a limited form of liquidity without disrupting the market. "Both moves are an indication that the dollar's status as a reserve currency is not what it used to be," Eichengreen wrote. He argued that central banks have traditionally held dollars because U.S. Treasury securities offer deep liquidity, allowing them to be bought and sold freely in interventions. "But not now, at least not in unlimited quantities," he added. This strikes at the core of dollar dominance, which relies heavily on the immense size and depth of the U.S. debt market. By signaling that Treasuries cannot be freely used in all circumstances, Washington risks undermining the very reason investors hold them. "The bottom line is that Washington, fearing the consequences for U.S. financial markets, is reluctant to see foreign central banks use their dollar reserves," Eichengreen concluded. "This is telling us that the dollar is not the attractive reserve currency it once was. When this message sinks in, other countries will redouble their search for more attractive, readily usable alternatives." Kieran Tompkins, a senior climate and commodities economist at Capital Economics, echoed that sentiment in a note last Friday. He argued that the U.S. effectively pressured Japan not to sell dollar assets, which in turn enhances the relative appeal of holding gold. Central banks have been steadily diversifying into gold for years, reducing reliance on the dollar. Some of this trend is unrelated to de-dollarization, driven instead by concerns about fiscal, inflation, and geopolitical risks. But it also reflects a desire to reduce vulnerability to U.S. sanctions that leverage the dollar's ubiquity, eroding another pillar of its dominance as the top currency for international transactions. "Central bank gold buying has slowed this year, but that is likely in response to soaring gold prices caused by speculative momentum. However, the ability of central banks to conduct FX operations without triggering concerns from U.S. administrations about the impact on U.S. bond markets could provide fresh impetus to central banks' demand for gold," Tompkins predicted. Yet not everyone is convinced that the dollar's grip is loosening. Strategists at Goldman Sachs offered a counterargument in a separate note, downplaying fears that the U.S. might prevent debt holders from selling Treasuries in the future. They pointed to Japan's use of the FIMA repo facility as evidence of dollar strength, not weakness. "We believe Treasury's actions and the availability and utility of the FIMA facility help demonstrate that no one else can come close to competing with the U.S. dollar's usefulness, network effects, and supporting infrastructure right now," Goldman added. The debate underscores a growing tension: while the dollar remains unmatched in many respects, the mechanics of this intervention may have inadvertently revealed cracks in its foundation.