New Delhi, March 2 -- PRESIDENT DONALD TRUMP likes to launch his military campaigns on a weekend. In June, during a 12-day war started by Israel, American forces bombed Iran's nuclear sites on a Sunday. They captured Nicolas Maduro, Venezuela's former dictator, on a Saturday in January. And they hit Iran again on February 28th, a Saturday, in dozens of strikes co-ordinated with Israel that killed Ali Khamenei, Iran's Supreme Leader. One theory is that Mr Trump deliberately pushes the button when oil markets are closed, to let the dust settle and prevent prices from going haywire. If so, it is unlikely to work this time.

Markets were already nervous before the weekend. On Friday oil closed at $73 a barrel, the highest since July. This was...