Defence spending is a difficult one.
Up until recently the UK has been spending more and more money on smaller and smaller numbers of state of the art equipment. F35 fighters, astute class submarines and type 45 destroyers are some examples of this.
These are the very best, but highly expensive. They take a long time to build, and are expensive to operate, but are world class in terms of capability. We do not have that many of them because they are so expensive.
One of the issues is that because these systems are so expensive to operate and repair with defence spending and defence priorities being lower down the pecking order we have been spending less and less money maintaining these few state of the art weapons. What that means is now a significant % of them (and we didn't have many to start off with) are laid up and unusable because we haven't been spending the money to properly maintain them.
This is against the backdrop of the Russian Ukraine war. Wars tend to push technology and change strategies. New tactics are developed. So both Russia and Ukraine have been developing new strategies to wage war. Many of these involve low tech but numerous weapons that are cheap to build and can overwhelm high tech defences (such as ours) through sheer numbers rather than advanced technology. This has also been shown in the US-Iran war, where again the threat of numerous low technology weapons against the US high technology weapons has been difficult for the US to deal with.
So in summary the UK has some issues. Firstly a high % of our sophisticated weapons are out of action. Secondly the weapons we do have are not good in addressing the cheap numerous threats. Thirdly there has been a resurgence in Russia as a potential threat to us.
So there must be some good news and there is. The good news is we are developing new weapons to deal with the numerous cheap weapons. But doing this costs money. We can get our more sophisticated weapons back in action, but again this costs money. Or, the alternative is we can do none of this and hope we will be able to muddle through.
For me in the future we need to balance the weapons better to address both the high and low technology threats. Building expensive nuclear submarines for example to address submarine threats in the north sea is silly. We only need those for power projection. So we need to have a better balance of numerous low tech and high tech weapons. Again making the change is going to cost money.
To me the defence spending in the UK very much mirrors a lot of spending in the NHS. Where medics often want the best technology, not necessarily to spend money on the technology that will do the most good. This is why for example scans in the Far East may cost much less than in the UK. The UK has the best equipment, but has low throughput, whereas in the Far East they have much more lower tech equipment that can be used to treat more people. The diagnostic capability is of course lower but the overall good that can be done is higher. A philosophy to think about.