The author is a Reuters Breakingviews columnist. The opinions expressed are his own.
The Japanese yen has strengthened unexpectedly by about 4 percent over the last month and it could rise further if the U.S. Federal Reserve delays a rate hike and the dollar weakens.
That the European Central Bank will have to soon add to its massive stimulus programme is fast becoming the consensus view among economists, although how it will do that effectively is far from clear.
An interesting weekend intervention by ECB policymaker Yves Mersch who said there was no question of winding up QE early and that inflation, still skulking around zero, would stay there until autumn then rise sharply late in the year towards 1.5 percent.