The Guardian reports:
SAS personnel ‘refusing to answer’ questions about alleged extrajudicial killings in Afghanistan
Judge leading UK inquiry says most operators using privilege against self-incrimination to refuse to provide information
The difficulty in prosecuting soldiers of elite regiments of war crimes is already well known.
Australian decorated SAS soldier Ben Roberts-Smith has not been convicted; he was charged with five counts of war crimes but has not yet faced a trial that resulted in a convictions for war crimes.
Like the Marine A case in the UK, the real problem is that guys have been caught out and in these cases no-one wants to face the music. Although in Marine A's case this was just over 3 years in prison for shooting an unarmed, wounded Taliban prisoner.
https://www.bbc.co.uk/news/uk-39740931
Everyone knows that war crimes are rampant in all wars so the best defence is not to talk about them.
Omerta.