Current defense policy isn’t a subject I follow very much, and even if I did so it would only be with the limited amount of information that’s available in the open press, so I can’t offer the kind of expert opinions that could be provided by the board members who are either in the military or who (like rjpeters) work with the military – but for whatever they might be worth, here are a few thoughts.
I’d start by asking a variant of Garg’s question: what (as opposed to whom) is behind the proposal? Is the stated purpose to save money overall? Or is the purpose to save money in one place so it can be spent elsewhere? I recently heard, for example, that the A-10 Thunderbolt II is being contemplated for retirement, and that some people have speculated that the (not-so-secret?) purpose of this move is to divert money towards continuing the development of the super-expensive F-35 Lightning II fighter. Whatever the case may be, I think it can be argued – as Paul Kennedy did in The Rise and Fall of the Great Powers – that great powers like the US have to strike a tricky balance when it comes to defense spending: making sure that they spend enough money in the right places to be able to deal with threats to their national security and to maintain their status on the world stage, but not to the point where they drive themselves into bankruptcy (which is partly why the USSR collapsed a couple of decades ago). Modern military forces are extremely expensive, especially when a country tries to stay at the cutting edge of military technology, so even a country as enormously wealthy as the US has limits on what it can spend on its armed forces (especially if one wants to adopt the position that a country should only spend what it can afford to pay for in cash within a balanced budget rather than with credit within a deficit budget).
The issue can therefore be approached from two angles. The first approach is to determine how much defense (and what kind of defense) one needs to achieve a country’s national security objectives, and to then find a way to fund this plan accordingly. The second approach is to determine how much the country can afford to spend on defense, and to then devise a plan to make the best possible use of the dollars available – the catch being that this may result in a defense posture which is considered inadequate. A great power might even (to pick up Kenndy’s argument again) have to conclude that it no longer has the military and economic power it needs to maintain its preeminence on the world stage, which is what happened to Britain during the period running roughly the 1930s to the 1960s.
Britain is actually an interesting example of this dynamic on account of two defense policies it had in the decades prior to WWII. On the one hand, Britain’s traditional policy was that its navy had to be big enough and powerful enough to defeat the world’s next two largest navies combined. (This is along the lines of the point I mentioned earlier about determining what size and type of armed forces are, in a nutshell, “good enough, but not too much”). WWI and the Great Depression both put severe strains on this traditional policy, so Britain switched to a second approach: the “ten-year rule”, which was brought in as a cost-saving measure. The ten-year rule basically said that, for military planning and procurement purposes, Britain would assume that another war would not break out for another ten years, hence justifying reductions in defense spending. The problem, however, was that Britain kept extending the ten-year window year after year (in much the same way that the projected realization of controlled nuclear fusion has been a consistent “fifty years from now” for the past several decades). The result was that Britain had a lot of catching up to do when it finally decided (around 1936, I think) that it had better stop deluding itself that a new war could be postponed indefinitely.
Anyway, as Garg says, without more details, it’s hard to provide more than general comments, especially from a limited civilian perpective. I’m quite glad that none of these policy decisions rest on my shoulders.