Saudi Arabia says that it will do the heavy lifting under the latest round of Opec cuts, cutting deeper than its commitment if necessary. Its willingness to do so is not in question, after all it did exactly this under the previous round of cuts in place since January 2017. Yet it can exceed its commitments and still post a year-on-year production increase.

The kingdom’s apparent munificence is taking place from record heights and it can afford to “cut” from these and...