Sanders first target would be nuclear forces. He has repeatedly argued that they are too expensive and pledged to cut $100 billion in nuclear spending over 10 years. Sanders would likely embrace a doctrine called minimum deterrence; that is, maintaining only enough nuclear capability to threaten devastating retaliation. Although force definitions for minimum deterrence vary, 300 to 400 warheads is a rough estimate. That compares with the current New START cap of 1550. Getting down to that level would require retiring the entire ICBM force, retiring the nuclear bomber force, and reducing the sea-based leg to about six submarines from the current 14. The new Long Range Strike Bomber program (LRSB) would be terminated because of its high cost, even though its primary mission is conventional. There would be commensurate reductions in the National Nuclear Security Administration, which develops and produces nuclear weapons. One of the weapons labs, likely Lawrence Livermore in California, would have to be shuttered. All this would save real money, about $15 billion per year, but not nearly enough.
Sanders has also been critical of national missile defense, so one would expect radical reductions there. But potential savings are not that large. The budget of the Missile Defense Agency is $8.1 billion, of which about half is for national missile defense and the other half is for theater missile defense. Programs in theater missile defense, such as THAAD, AEGIS SM-3, and PATRIOT have had much more successful testing records than the national missile defense programs. Because theater programs defend US forces overseas and our allies, they have also had bipartisan political support. So there might be savings of $1 billion to $2 billion per year but, again, not nearly enough to close the gap.
Heres what you would need to do to produce the savings needed.
◾Reduce the active Army to about 250,000 soldiers, down from todays level of 475,000. To compensate, the reserves might be reduced less, to perhaps 290,000 for the National Guard and the Army Reserve. This would be consistent with Sanders statements that he wants to decrease Americas overseas presence, particularly in wealthy regions like Europe and Japan. The Army would become a surge force rather than a forward-deployed force. Its capability would still be formidable, perhaps 25 total combat brigades, but it would take much longer to get overseas. Think World War Two, not Desert Storm.
◾Shrink the Navy to about 160 ships with maybe five carriers (Cold War weapons). It would take a long time to get to this level, even by retiring ships early. The Navy could live off its existing inventory for a decade or two. Nevertheless, the smaller fleet would over time mean a much reduced overseas presence. Even giving preference to the Pacific theater, withdrawing entirely from Europe and mostly from the Middle East, the Pacific rebalance would be radically scaled back. Countries in the Western Pacific would likely make their best deal with a rising China rather than relying on a withdrawing United States. To maintain any sort of shipbuilding industrial base, the Navy would need to continue to build a few ships, but some shipyards would still have to close. Based on recent history, NASCO in California and Bath Iron Works in Maine would certainly go out of business. So might the Electric Boat Company in Connecticut.
◾Switch the Air Force from building fifth generation aircraft like the F-35 (incredibly wasteful) to extending the life of its fleet of legacy aircraft like F-16s and F-15s. The Air Force would still have a formidable fifth-generation force in the F-35s already built and the existing F-22s, although that force would be much smaller than planned.
◾Reduce the Marine Corps to a strength of about 90,000 (active). It would still be the largest marine corps in the world but would not be able to maintain the forward deployments that have been customary since the Second World War