NEW YORK (AP) — A widening war in Iran has halted oil tankers, made targets of refineries and spooked investors worried about the cascading impact of spiking energy prices. If it might seem like the ideal time to dip into the world’s emergency oil stockpiles, global leaders have so far responded with reluctance. Here is a look at the energy supplies that countries hold and when they tap them: Many countries have reserves of oil Since war erupted in the Middle East on Feb. 28 with U.S. and