Japan just spent roughly $72 to $73 billion trying to prop up the yen. And according to the country’s top currency diplomat, Washington didn’t so much as raise an eyebrow.

Atsushi Mimura, Japan’s Vice Finance Minister for International Affairs, confirmed that the United States has not objected to Japan’s currency intervention since late April. In a June interview, he went further, stating the two nations are “in complete agreement” on foreign exchange issues.

The intervention playbook

Japan launched its yen-buying operation on April 30, 2026, marking the first substantial intervention since July 2024. The total buying across April and May amounted to approximately 11.7 trillion yen, or between $72 and $73 billion.

The Japanese currency had been sliding toward 40-year lows, driven by a widening gap between the Bank of Japan’s ultra-accommodative monetary policy and tighter rates elsewhere. By June 30, the yen hit a fresh multi-decade low despite all that intervention spending.

Mimura had issued what he described as a “final warning” to markets on April 30, coinciding with the start of intervention. Sources indicate that warning remains in effect, even though Mimura went largely silent on the topic after early May.

Why Washington’s silence matters

When Mimura says Washington has raised no objections since the April intervention began, he’s communicating something important: Japan has diplomatic cover for what it’s doing. The “complete agreement” framing suggests that the US views yen weakness as a shared problem, not a competitive advantage Japan is trying to exploit.

For context, when Japan last intervened aggressively in 2022, it spent roughly 9.2 trillion yen across multiple operations. The current round already exceeds that figure.

What this means for investors

The yen continued weakening even after Japan deployed tens of billions in buying pressure. Market analysts have consistently pointed out that without a fundamental shift in Bank of Japan monetary policy, interventions function more like speed bumps than roadblocks.

The Bank of Japan has shown limited appetite for the kind of aggressive rate hikes that would structurally support the yen. As long as that policy gap persists between Tokyo and other major central banks, the gravitational pull on the yen remains downward.