Fighting Deflation: ECB Needs Support in Lonely Battle

The heat is on. Eurozone inflation fell sharply back into negative territory in February, to minus 0.2% from 0.3% in January, data showed Monday. Even amid a global debate about the need for policy makers other than central bankers to take responsibility, the European Central Bank faces a huge near-term test.

The decline in headline inflation to a one-year low—partly driven by a large fall of 8% in energy prices from a year ago—isn’t the only problem for the ECB. So-called core inflation, which strips out energy, food,...