CAMP LEATHERNECK, Afghanistan – Defense officials and military observers alike have jokingly referred to the Marine Corps’ regional command here as “Marine-istan,” a nod toward the thousands of Marines deployed in the region. There’s a significant division in the two provinces that make up the area of operations, however. When Regional Command-Southwest was established in spring 2010, Helmand province was home to a muscular insurgency, while sparsely populated Nimroz province was relatively tranquil. Two years later, Nimroz has continued to progress. Nestled in the southwest corner of Afghanistan along the Iranian and Pakistani borders, Nimroz doesn’t require the heavy sustained…