Donald Trump could scarcely have chosen a more treacherous economic moment to tear up the “decaying and rotten deal” with Iran.  The world crude market is already tightening very fast. Joint production curbs by Opec and Russia have cleared the four-year glut of oil. There is no longer an ample safety buffer against supply shocks. The geopolitical “premium” on prices has returned. The Maduro regime in Venezuela is in its last agonies. The country’s oil industry is imploding as spare parts run out, taking 700,000 barrels a day (b/d) off the global market over the last year. North America has hit an infrastructure crunch. There are not yet enough pipelines to keep pace with shale oil output from…