War veteran Ben Roberts-Smith has told a Sydney court Australian soldiers were permitted to use “whatever force was necessary” to arrest insurgents in Afghanistan, including punching those who were fighting back.

Mr Roberts-Smith is being cross-examined on his fifth day in the witness box during a high-stakes defamation trial against three newspapers in the Federal Court.

The 42-year-old is suing The Sydney Morning Herald, The Age and The Canberra Times, along with three journalists, over several 2018 stories which reported allegations of wrongdoing related to his time deployed in Afghanistan.

The publisher of two of the papers, Nine Entertainment Co, is relying on a defence of truth and Mr Roberts-Smith has denied all wrongdoing, including his alleged involvement in up to six unlawful killings.

Under questioning by Nine’s barrister, Nicholas Owens SC, Mr Roberts-Smith agreed it was never permissible, under both the rules of engagement and the Geneva Conventions, to kill someone once they became a “person under confinement” (PUC) of the Australian soldiers.

He said all “fighting-aged males” in a “target building”, such as a compound, would become PUCs, while care was taken to not touch women or children due to cultural sensitivities.

“Is there a strict definition in terms of age about a fighting-aged male?” Mr Owens asked.

“There is no strict description of a fighting-aged male. Effectively anyone that you felt was old enough to directly take part,” Mr Roberts-Smith replied.

Mr Roberts-Smith was then questioned about the use of force with PUCs.

“You could use what force was necessary and required to effect the arrest of the PUC,” the veteran said.

“Would that include punching them?” Mr Owens asked.

“If required, yes,” he said.

Force such as a punch would be required “if they were fighting back”, he added.

Mr Roberts-Smith said soldiers were also permitted to physically move someone if they were non-compliant.

He could not recall if the process for placing a person under confinement and bringing them back to base was different for an adult as opposed to an adolescent.

Mr Roberts-Smith has previously told the court some male insurgents he “engaged” with were as young as 15.

The process of placing a person under confinement is central to the case, as Mr Roberts-Smith’s is arguing he was defamed by imputations that he “broke the moral and legal rules of military engagement” and “disgraced his country”.

He has today agreed that at all times in Afghanistan, it was his understanding that if a soldier killed a PUC in any circumstance they would have committed murder.

He agreed that it would effectively break the legal and moral rules of military engagement.

Mr Roberts-Smith has previously denied killing any person who had been placed under the control of the Australian forces.

The veteran also agreed that it would never be permissible to “order, direct or encourage” another soldier to kill a PUC, and that there would be an obligation to take reasonable steps to prevent that conduct if the situation arose.

Today he also explained the evolving techniques of the Taliban insurgency, such as placing improvised explosive devices against walls that Australians would use for cover, using cornfields for ambushes, and firing upon Australian forces as they were “extracted” from missions by helicopter.

Mr Roberts-Smith is also suing over what he claims were defamatory imputations that he bullied colleagues in the Special Air Services Regiment (SAS) and committed an act of domestic violence on a woman in a Canberra hotel room.

He has denied all the allegations.

–ABC