Markets appear calm about recent challenges to Federal Reserve independence, but that quiet won't last. The central bank's credibility rests on its ability to set interest rates without political pressure. When that autonomy erodes, investors eventually demand higher premiums for holding U.S. Treasuries, pushing up borrowing costs across the economy.

History provides clear warnings. The 1970s inflationary spiral began when political pressure kept rates too low for too long. Markets tolerated it until they didn't.

The same pattern could repeat if traders sense the Fed is taking orders from the White House instead of following economic data. Bond vigilantes have been dormant for years, lulled by consistent policy. Yet Treasury yields are the world's benchmark for risk-free returns.

Any hint that rate decisions serve political cycles rather than price stability will force investors to reassess the value of long-term debt. That reassessment rarely happens gradually. For now, traders focus on inflation reports and employment figures.

But political attacks on Fed officials are growing louder. Markets may shrug today, but they keep score over time. When confidence breaks, the reaction is sharp and expensive.