Australia faces a substantial gap in its submarine capability throughout much of the 2030s, raising concerns about national defense readiness in a strategically sensitive region. The country’s current fleet of six Collins-class conventional submarines is aging, with most vessels either undergoing maintenance or sidelined due to corrosion and other technical issues. Reports indicate that five of these submarines are currently non-operational, largely because of prolonged industrial action and persistent maintenance delays.

Defence Minister Richard Marles has maintained that the Collins-class submarines will remain "potent and highly capable" for the foreseeable future. However, planned upgrades to extend their service life have been significantly reduced, casting doubt on their reliability for frontline deployment. Military analysts warn that these submarines, which have been in service since the 1990s, are unlikely to be combat-effective against modern nuclear-powered adversaries. Instead, they may be relegated to intelligence gathering and training roles, akin to the limited use of the retired F-111 strike bombers.

The issue of undersea defense deficiencies is not new for Australia. As early as 2011, reports highlighted periods when no Collins-class submarines were operational, leaving a temporary capability void. Since then, successive governments have grappled with maintaining a continuous and effective submarine force amid technological challenges and budget constraints.

Australia’s future submarine capability hinges on the AUKUS security partnership with the United States and the United Kingdom, under which the country plans to acquire at least three Virginia-class nuclear-powered submarines. These vessels are expected to enter service in the 2030s, representing a significant leap in strategic undersea warfare capacity. Although the Albanese government supports this initiative, the lengthy interim period before the new submarines arrive is raising concerns among defense experts and policymakers.

There have been discussions about short-term alternatives to mitigate the capability gap, such as leasing advanced conventional submarines from allies like Japan. However, the government, led by Foreign Minister Penny Wong, has dismissed these proposals for now, emphasizing reliance on the existing fleet and the eventual delivery of AUKUS submarines.

Observers caution that the success of the AUKUS program is not guaranteed and warn of the historical tendency for defense projects in Australia to encounter delays and cost overruns. As the strategic landscape in the Asia-Pacific becomes increasingly complex, the prospect of a diminished submarine force leaves Australia potentially vulnerable beneath the seas for an extended period, underscoring a long-standing national security challenge.