Move over John Kerry, and make room for Janet Yellen.

An odd thought, perhaps, given that diplomacy is U.S. Secretary of State Kerry¡¯s thing, while Fed Chair Yellen tends to monetary policy. But a unique feature of today¡¯s fragile and interconnected markets is how geopolitical fallout, particularly in Asia, will increasingly force the Federal Reserve to scale back its tightening ambitions.

¡°The U.S. central bank is very much carrying out actions to help soften problems that would usually be the role of the State Department,¡± Boston bond-market veteran Dan Fuss said in Tokyo. While the Fed¡¯s mandate is domestic stability, it faces unprecedented considerations about destabilizing far-away nations Washington hopes to keep stable. ¡°That¡¯s a huge concern,¡± Fuss said. And a fast growing one.