How should we interpret the fact that unit labour costs have been growing faster in the recent period in the euro zone?

Since the end of 2017, unit labour costs have been accelerating in the euro zone, which could point to a rise in core euro-zone inflation, and thereby prompt the ECB to normalise its interest rates after the summer of 2019. But we seek to understand what accounts for the acceleration in unit labour costs: Nominal wage increases reacting to the fall in the unemployment rate and to recruitment difficulties ? If that is the case, the faster rise in unit labour costs and the resulting rise in core inflation are robust, and will prompt the ECB to react; A partial indexation of nominal wages to headline inflation, the rise in which is due to the rise in energy prices and in the oil price? If that is the case, a stabilisation of the oil price would eliminate the faster rise in unit labour costs; The cyclical weakness of productivity in 2018, due to the slowdown in growth that itself is explained by the decline in real wages caused by the rise in the oil price? If that is the case, the acceleration in unit labour costs will be temporary. An observation of these trends and econometric analysis show that the dominant effect is the rise in the oil price, the two other effects (labour market pressure, declining productivity gains) appear, but are smaller. We can then conclude that a large part of the acceleration in unit labour costs in the euro zone will disappear if the oil price stabilises.