The U.S. Federal Reserve doesn't just set policy for the United States — because the dollar underpins so much of global trade and debt, a Fed decision effectively sets a reference point the entire world reacts to. When the Fed raises rates, money often flows out of emerging markets and into U.S. assets chasing the better, safer return, which can weaken other currencies and make it more expensive for those countries to repay dollar-denominated debt.
This is sometimes called "importing" monetary policy: a country's central bank may be forced to raise its own rates — even if its domestic economy doesn't need it — just to keep its currency from collapsing against the dollar.
It's a quiet kind of power that rarely makes headlines outside financial press, but it explains why so many seemingly unrelated national economic stories trace back to the same two-day meeting in Washington.
The bottom line: No economy today is truly isolated — a policy decision in one country can become an involuntary policy decision in another.