Less than 20 miles off Iran’s shallow coastline sits a rare island made of hard coral — a natural, geological platform rising from the Persian Gulf that’s perfect for one thing: exporting oil. This is Kharg Island, a crucial outcrop 5 miles long that might be about to become central to the Iran war. Almost one month into their joint military campaign, the United States and Israel have killed a host of senior Iranian leaders and bombarded key sites across the country. But, in response, Iran has attacked Israel and its Gulf neighbors and blockaded the vital Strait of Hormuz trade route, delivering a global economic shock that has sent energy prices surging and threatened food shortages for billions. President Donald Trump has talked up negotiations with Iran, which in turn has disputed any progress. He is also sending thousands more American troops to the Middle East, drawing suggestions from Tehran that Trump is buying time for a ground operation.…