Australia will look at buying 24 more Boeing F/A-18 Super Hornets in the event of any major new setbacks to the controversial Lockheed Martin Joint Strike Fighter project, Defence Minister Stephen Smith said on Thursday.

That means Australia could buy fewer stealth F-35 Joint Strike Fighters than originally planned and is another sign that development partners are growing frustrated by delays and cost overruns to the $396 billion programme, which is the costliest programme in Pentagon procurement history.

The announcement comes a day after Canada also said it would look to other options for its jet fighters due to mounting concerns over the development and cost of the F-35s.

“Australia’s air combat capability is a vital part of our national security framework. The government will not allow a gap in our air combat capability to occur,” Smith said on Thursday.

Australia foreshadowed the decision in May, when it delayed orders for its first squadron of F-35s by two years to help with budget savings and to put Australia’s F-35s on the same timetable as those for the United States.

Australia originally planned to by up to 100 F-35s, for up to $16.4 billion, but has made no commitment beyond its first 14 aircraft. Australia has committed to two joint strike fighters to be delivered in 2014-15, but they will remain in the United States for testing and pilot training.

It was due to decide by the end of this year on the timing of its next order of 12 F-35s, but that decision has now been pushed back to next year, while the government considers options to replace its Classic F/A-18s.

Australia’s fleet of 71 Classic F/A-18 Hornets entered service between 1985 and 1990 and were due to retire by around 2020.

Australia also has 24 of the new generation F/A-18F Super Hornets, which entered service in 2010 and 2011, and 12 of those have been upgraded with sophisticated U.S. jamming equipment.