Up to another 50 were to be deployed on Friday, as well as an additional 40 ADF personnel, which would bring the contingent up to 116 so far.

Major General Jake Ellwood described the situation as "volatile".

"We don't provide details about our rules of engagement, but what I can tell you is that our soldiers, sailors and aviators can protect and defend themselves," he said.

Soldiers and police from Australia are also afforded immunity: They "shall be immune from arrest, detention and all legal proceedings in Solomon Islands courts and tribunals in relation to actions that are taken in the course of, or are incidental to, official duties."

The treaty adds that they "shall not be compelled to appear or give evidence in legal proceedings of any kind in Solomon Islands courts and tribunals", however, Australia can waive that immunity.

Additionally, Australia — with the consent of Solomon Islands — may invite third states to contribute to the deployment.