Concerns about the adequacy of a plan to replace the U.S. military's humvee fleet with a newly designed, next-generation family of vehicles have prompted the Pentagon to put the brakes on the Army and Marine Corps' Joint Light Tactical Vehicle competition. The misgivings stem from questions about technical maturity, shifting requirements and adequate funding. As a result, John Young, the Pentagon's acting acquisition executive, has directed the two services to head back to the drawing board to develop a "robust...