Army Secretary Dan Driscoll is poised to assume temporary leadership of the Bureau of Alcohol, Tobacco, Firearms and Explosives, a rare dual appointment that places the 38-year-old at the helm of two high-stakes federal institutions, according to three defense officials familiar with the matter. The move comes at a pivotal moment for both agencies. The ATF continues to draw partisan scrutiny over firearms regulation, while the Army is undergoing a strategic transformation to counter China's