First it was the Fed, then the ECB (which last week tapered when it reduced the monthly amount of bond purchases under its QE program). Now attention shifts to the Bank of Japan, because as the WSJ writes, one of central banking’s most aggressive easers – Kuroda’s Bank of Japan – may soon have to think about tightening for the first time since 2007.

While it has yet to permeate the markets (confirmation would send the Yen soaring), the latest buzz in Japanese monetary-policy circles is that the BOJ may have to lift the 10-year government-bond target from a recently set zero, in the process tightening financial conditions even more. Indeed, as the because as the WSJ writes, such a changed view on BOJ policy is quite a turnaround.

Just a few months back investors and economists world-wide were discussing what would be the next easing steps in the bank’s 15-year fight to boost the economy and produce inflation. More certainly seems needed: Japan’s economy grew more slowly than expected in the latest quarter and prices are falling.

So why switch gears now? Blame Donald Trump, stupid, whose miraculously adverse impact on the Yen has been more profound than either of Japan’s recent QEs…. and that is before Trump is even inaugurated, or reveals any of the details behind his fiscal stimulus plans.

The U.S. dollar and Treasury yields have been climbing since soon after Trump was elected president on Nov. 8, triggered by expectations that his policies would boost U.S. growth, inflation and interest rates. So far, that has been good for Japan, where the weaker yen is brightening exporters’ prospects, helping send Tokyo stocks to 11-month highs. A weaker yen bolsters their bottom lines by making their products cheaper overseas and inflating the value of repatriated income. As of Friday, one dollar buys ¥114.50, 9.6% more than the day before the U.S. election.

While that may be fine as far as it goes, according to various central-bank watchers who spoke to the WSJ, the BOJ’s latest easing policy raises the risk of far greater, and potentially damaging, depreciation. That is because as a result of the curve “anchoring”, the wider the yield spread between JGBs and foreign bonds, the greater the outflows, the more aggressive the selling of the Yen. For example, since U.S. Election Day, U.S. 10-year Treasury yields have risen to 2.426% from 1.862%, far outstripping the Japanese benchmark bond’s rise to 0.056% from minus 0.064%.