Today’s announcement that the government is going to spend more than $12 billion on F-35 Joint Strike Fighters has already caused a lot of head scratching in this the “age of austerity”. And that’s fair enough — every dollar the government spends on defence isn’t available for anything else the punters might want.

Government is all about prioritising policy and how it collects and spends its resources. So even if you’d rather have another hospital or school, it’s worth understanding the reasoning behind this sort of decision. Here are a few answers to questions I’ve been getting all day (and for the last few years) …

Aren’t prices of the Joint Strike Fighter still climbing?

Actually, no. The price is now trending downwards, and the last couple of production batches have come in at lower prices than United States budget estimates. That said, the F-35 was initially sold as a cut-price fighter for the 21st century, which it isn’t. It continues the trend of every generation of fighter aircraft being significantly more expensive than the previous one.

Do these things work? I hear that the F-35’s development continues to be a problem …

This is partly true. The program to develop the aircraft was a bit of a shocker in its early years. Things are much better now, but a few challenges remain, not least of which being the software required to make it work as designed. The major overhaul of the program, which began in 2010, produced a timetable that’s mostly holding — certainly far better than previous performance.

If it’s not ready, why do we need to decide now?

Given that the air force’s Hornet strike fighters reach the end of their life not long after 2020, the options are pretty limited. We could buy a less capable (but more technically mature) alternative, or even decide that we don’t need a fast-jet air force. The Kiwis took the latter option, but their local maps don’t look like our local maps, so that was always an unlikely position for an Australian government to take.

In any case, the decision to approve the purchase of F-35s doesn’t commit us just yet. Contract signature could still be two years away. By then the aircraft should be entering service with US forces, and we should be much better placed to make an assessment.

Professionals in the military are still concerned about the performance of the aircraft …

In talks with the USAF and RAAF, the feedback I get about the performance of the F-35 is overwhelmingly positive. If anything, the problem is that enthusiasm from the services that will employ the F-35 is so strong that it’s difficult for them to hear the case for lower-cost but less capable options.

Is this about sucking up to the US?

There’s certainly a strong alliance angle to this purchase. Backing away from the JSF would certainly cause some ripples in Washington. And we’re following the path of other US allies in the form of the UK, Japan and Korea in deciding to go with the F-35.

Won’t Chinese and Russian aircraft eat the F-35 for breakfast?

There’s a few very vocal critics of the F-35 who claim that the F-35 would be a sitting duck for what they assess to be much more capable aircraft appearing in Russia and China these days. I don’t buy that — this would have to be the biggest technical error of all time on the behalf of the US and those customer countries (including Singapore, Israel and several European nations) who collectively represent some of the savviest buyers of military hardware around.

And in any case, we’re not going to mortgage our defence capability to Russia or China, so buying the best Western fighter makes sense. (Our recent report discusses these issues in more detail.)

*Disclosure: Lockheed Martin, the prime contractor on the F-35 program, is a corporate sponsor of ASPI