The contradictions in Japan’s efforts to protect the yen while slowing the pace of rising bond yields are becoming increasingly clear in currency and debt markets.

While Thursday presents a slightly different picture after the Federal Reserve kept rates on hold, the action in Tokyo on Wednesday underscores Japan’s huge challenge.

The day began with the nation’s top currency official at the Finance Ministry giving one of the starkest warnings yet that authorities were ready to intervene in the foreign exchange market to stem the yen’s fall. By lunchtime the Bank of Japan was preparing to wade into the debt market to slow the speed of the 10-year bond yield’s ascent toward 1%.