The published record on Westport and Cockburn Sound

The record in order

Westport was proposed, sited, and made state policy before the AUKUS submarine arrangements existed. Everything published since, including the project’s own business case, has been published into a Cockburn Sound that changed underneath it.

1. Before AUKUS existed

   Before September 2021

   Westport becomes Western Australian state policy

   The state commits to moving its container terminal about 20 kilometres south, and to building it as an automated port, from Fremantle Harbour to Kwinana on the eastern shore of Cockburn Sound, at a cost of AUD $7.2 billion. No allied nuclear submarines are based in that water, none are planned, and no submarine maintenance facility is planned at Henderson. Every siting decision in the project is taken in that world.

2. September 2021

   AUKUS is announced, and the far shore becomes a submarine base

   Under the trilateral agreement, HMAS Stirling on Garden Island becomes the base where United States Virginia-class submarines will rotate alongside British boats. It sits about six kilometres across the water from the proposed terminal, and the maintenance facility those boats will use is planned for Henderson, on the same mainland shore. Every design decision above this line was made without any of it.

3. After AUKUS existed

   Late 2024

   The Westport business case is announced

   Three years after AUKUS, the project reaches its business case with the site unchanged. Construction is scheduled to begin within one to three years and the port is not expected to be fully operational until the late 2030s at the earliest, by which time the base will have been operating with American boats for years.

4. 5 August 2025

   The security report is circulated

   The Maritime Union of Australia, WA Branch, sets out the risks the relocation creates for submarine operations in Cockburn Sound: the shared entrance, the crossing of the submarine transit route, and the foreign-flagged composition of the traffic. This is the paper taken to Washington.

5. 11 August 2025

   Two retired ADF officers put questions on the record

   Air Vice-Marshal John Blackburn AO (Retd) and Commodore Vince Di Pietro AM CSC RAN (Retd) publish their assessment and ask the Australian Minister for Defence what risk work was done on the relocation after AUKUS, and how foreign-flagged vessels will be screened.

6. 12 and 13 August 2025

   The defense press picks it up

   Defense.info and Second Line of Defense report the siting problem, the shipping traffic projections, and the response from the Western Australian government.

7. Since August 2025

   The concerns are called wrong rather than answered

   The Western Australian Premier dismissed the concerns, saying the member who raised them was wrong. The public record still contains no risk analysis of the relocation conducted in light of what AUKUS brought to Cockburn Sound.

8. Still open

   The questions put to the Australian Minister for Defence have not been answered on the record. If that risk work has been done, publishing it would end this campaign.