According to a leaked draft of the 2013 defence white paper, Australia will take delivery of just two Lockheed Martin JSFs by 2020, indicating the government will need to buy a batch of rival Boeing F/A-18F Super Hornets, which are cheaper but older and less stealthy than the fifth-generation JSF (pictured).
''By the end of this decade, the ADF will . . . take delivery of three air warfare destroyers, two landing helicopter dock amphibious ships and the initial two F-35A Joint Strike Fighter aircraft,'' the white paper states.
While switching to the Super Hornets would not be a slug to the government budget - each is about $40 million cheaper than a JSF - it may mean money is wasted on training and maintaining two different types of fighters. And some experts say the Super Hornet would be challenged by some of Australia's neighbours' growing air combat capabilities.
The white paper states the government ''remains committed'' to acquiring the JSF but makes no mention of the next batch of 12 planes, which were expected around 2020.
This appears to confirm what Defence Minister Stephen Smith has hinted at and many experts have suspected: that Defence will replace some of the retiring classic Hornet aircraft with Super Hornets and end up with a mixed fighter fleet rather than the 100 Super Hornets originally proposed. Mr Smith has already asked the US about the price and availability of more Super Hornets.
Coalition defence spokesman David Johnston said the government had broken its pledge in the 2009 white paper to buy 100 JSFs that would have ''provided regional domination out to 2030''.
''The revelation . . . that this promise has been reduced to just two aircraft [by 2020] is a further testament to Minister Smith's incompetent handling of the Defence portfolio,'' he said.
Analysts broadly argue the JSF is the best fighter on the market, although many say the Super Hornet will probably suffice. Andrew Davies, senior analyst at the Australian Strategic Policy Institute, said the JSF was ''far stealthier and has a much more powerful and integrated set of sensors than the Super Hornet has''.
Australia would benefit from ''economies of scale on training and maintenance'' by having a single type of air force rather than a mixed fleet. ''Nonetheless, the Super Hornet is still frontline equipment with the US Navy and a powerful air combat capability.''
Sam Roggeveen, a strategic analyst and editor of the Lowy Institute's Interpreter blog, said the Super Hornet would represent a compromise but ''I would argue we don't need the JSF yet''.
Former defence minister Brendan Nelson, who bought Australia's existing 24 Super Hornets, said a mixed fleet to 2030 should give Australia what it needed, given other governments were hit by similar budget constraints as Australia.
''If the government did choose to (buy Super Hornets), Australia would still have extraordinary air combat capability and would be well placed in relation to our strategic competitors,'' he said.
But Peter Goon, a former RAAF engineer now with the independent experts Air Power Australia, was more pessimistic, saying Australia was ''already outmatched in the region'' on air combat. ''If you send out Super Hornets against the Sukhoi Su-35s, few if any of them will come back,'' he said.