Read up on your military history. That comradery is common at the start of so many past conflicts and they have a playbook.

They will handpick the first few groups of soldiers to go in specifically selected to be comfortable killing unarmed European civilians and soldiers alike. Oops, they commited an atrocity, my bad, I'll throw them in jail. But before that, the other side seeks their revenge and now the regular American soldiers who would have refused to fight a few days ago are getting slammed every nasty which-way and fight back. Both sides learn the other side is pure evil, and never notice the brass pulling the strings.