COULD BE CATALYST FOR $150 OIL Rising fears that a military conflict will erupt over Iran's nuclear program and block oil supplies from reaching markets has also helped push crude prices higher. The U.S. and Europe are tightening economic sanctions against Iran over what the West believes is Iran's attempt to build a nuclear bomb. World leaders fear Israel may be planning a strike against Iran. In response, Iran, which is the world's third largest exporter, has threatened to withhold its own oil deliveries and to block the Strait of Hormuz, through which one-fifth of the world's oil flows.