![Naval historian Norman Polmar says buying new nuclear-armed submarines is necessary to replace the aging ones in today's arsenal, but not in as many numbers as the Navy plans. Still frame from PBS Newshour Broadcast. 2015. Media file: sub_construction.jpg](/sites/default/files/07-31-15/sub_construction.jpg)
Naval historian and consultant Norman Polmar says buying new nuclear-armed submarines is necessary to replace the aging ones in today's arsenal, but not in as many numbers as the Navy plans. Polmar tells the PBS NewsHour alternatives must be explored.