The UN nuclear watchdog, the International Atomic Energy Agency's (IAEA) director-general, Rafael Mariano Grossi said that the agency will need to inspect the nuclear fuel-powered submarines in Australia before and after their deployment as part of a "watertight" agreement to guarantee that no fissile material is diverted.
As a way of limiting the possibility that fissile material could be diverted to making weapons, highly enriched uranium (HEU) will be delivered to Australia and will be installed in submarines to be assembled by Australia, and ready to use by the 2040s.
Inspections allow countries to verify that these types of nuclear devices—as well as nuclear weapons—are only used for their intended purpose under their nuclear nonproliferation treaty commitments.
The Aukus deal exploits a loophole in the 1968 Nuclear Non-Proliferation Treaty (NPT) that allows nuclear fuel used for non-explosive military uses like naval propulsion to be exempted from IAEA inspections.
Australia's Prime Minister Scott Morrison and other officials have admitted that they waited until after the deal was announced to talk to the IAEA.
The IAEA has expressed concern about the lack of transparency in the partnership between Australia, the United Kingdom, and the United States, known as Aukus, arguing that it could hinder the organization's nuclear safeguards mission.
While the Aukus alliance partners view the proposed deal positively, concerns in nuclear non-proliferation circles have been expressed, suggesting that it could set a precedent and be misinterpreted as a reason to proliferate military nuclear programmes.