The U.S. Navy has concluded no significant environmental harm would come from its proposed tripling of the size of a Nevada bombing training range. A massive expansion opposed by neighboring tribes, conservationists and at least one Democratic presidential candidate. Adding more than 1,000 square miles to the range at Naval Air Station Fallon 65 miles east of Reno is critical to meeting combat training needs for modern aircraft and weapons systems that have outgrown training capabilities over the past two decades, according to Navy officials.