"safest" unit for enlistment

Hi guy's, my 19 year old brother is determined to enlist in the fight against Russia. I've tried to talk him out of it and get him to volunteer in one of the charities on the ground in Ukraine instead but he wants to join the fight. He is looking at 3rd assault brigade, an assault unit sounds more dangerous to me than a more regular unit. Does anyone have any suggestion for a less risky unit? I know its an extremely dangerous war and no unit is safe but I would like him to have the best chance possible of surviving.

I would appreciate any advice and thank you all for your service.