US borrowing costs have climbed to their highest level in 19 years, underscoring how financial markets remain uneasy about the inflation outlook even after the Federal Reserve left interest rates unchanged. The move highlights a gap between the central bank’s decision to stand pat and investors’ concern that price pressures could intensify again.

A major source of that concern is the risk that Trump’s war with Iran could trigger a fresh inflation shock. Markets often react quickly to geopolitical conflict when traders believe it could push up energy prices or create wider cost pressures across the economy.

By keeping rates on hold, the Fed signaled that it is not rushing into another policy move despite the market’s rising anxiety. But higher borrowing costs suggest investors are demanding more compensation to lend over longer periods, reflecting uncertainty over inflation and the path of monetary policy.

The rise in US borrowing costs matters well beyond financial markets because it can feed through to mortgages, business loans and government financing. With inflation fears still active, the latest move points to a tougher backdrop for households, companies and policymakers alike.