Cuts of $500 billion over the next 10 years, representing roughly 5 to 8 percent of the Pentagon’s budget, would begin to take effect if the White House and Congress fail to reach an accord before the end of the year. The reductions would occur across the board. Even if there is a deal on taxes and spending to avoid the automatic cuts, it is a safe bet that the deal would impose additional budget reductions on the Pentagon.

Pentagon officials and military officers do not say it out loud, but their public inaction reflects a fear that any planning on cuts would amount to an invitation to Congress to make them. The Pentagon could then face larger reductions than it otherwise might as part of any deficit deal.

What programs could be vulnerable? Experts offer varying proposals, of course, depending on what branch of the military they think is most important and what sort of world they predict America will face.

Gen. Ray Odierno, the Army chief of staff, noted in a recent talk at the Center for Strategic and International Studies that there are only three large baskets of spending from which savings can be found: personnel costs; equipment costs, both for repairs and new orders; and training costs, like how many bullets are available for firing on practice ranges and how many hours can be logged in jet fighter training flights.

A study released this week by Todd Harrison and Mark Gunzinger of the Center for Strategic and Budgetary Assessments, a Washington research group, recommended protecting a series of military capabilities, which it called “the crown jewels,” necessary in a future combat environment. They included: Special Operations forces, cyberspace capabilities, underwater warfare systems and long-range surveillance and strike aircraft, both manned and unmanned.