Vixen trials involved safety testing. They were about assuring that the core of a nuclear weapon would not accidentally undergo criticality in the event of a fire or unintended crash. These were messy, for a successful test subjected the core to high explosives in the hope that it simply scatters rather than undergoes criticality. These tests sometimes involved some yield from fission, but in every case this was less than the yield from the weapon's conventional explosive component. The British Government's position was that so long as the nuclear explosion component was less than there was no violation of the Partial Nuclear Test Ban Treaty, which was then under discussion, but no such limit was agreed upon. While the AWTSC could determine whether there were public health and safety issues with a test, it could not assess whether there were political issues. However, after some consideration, the Australian Government did approve the proposed Vixen test program.