Diesel futures traded sharply higher Tuesday, as doubts mounted about the likely impacts of the Trump administration’s latest efforts to push prices down. U.S. diesel futures were up 5% by midday to their highest level in weeks. In Europe, diesel futures rose by about 3.8%, while gas futures spiked to levels not seen all year. A move higher in futures markets typically signals that prices will climb in the coming days. Already, the average nationwide price of diesel is up 70% since the U.S. and Israel attacked Iran on Feb. 28. The cost of unleaded gas has risen by more...