Is the Army broken? That question, posed by “Frontline” producer Michael Kirk, is at the heart of “Rumsfeld's War,” an exploration of the status of the U.S. Army as it fights in Iraq. The program also profiles the secretary of defense, recalling his first stint at the Pentagon in the 1970s, and tracing his efforts to make the Army “quicker and more nimble” since he returned to the office in 2001. But in doing so, Kirk wonders, “Has he plunged it back to the state it was at the end of Vietnam?”