How would you react to an E2 who "smart mouths" you in formation?

Well during my time I would leave him standing until I releast the rest of the platoon to go do their assigned jobs. Then I would make the private start doing pushups while I went in the off and talked to my other NCOs. Then we would probably have a trash can drill on this young private to help him straighten up his attitude. Or I would march his whiny little ass into the First Sergeants office and being him up on a couple different charges that I can think of off top of my head and request that he be put in solidary confinement until his, at minimum, Art 15 hearing.
Now a days who knows what they would do or be allowed to do. I think they are starting to develop wimps not soldiers. A lot of the guys I've seen coning out of training, hell even some coming out of Marine boot camp are going to crap their pants the first time they are put in a real life fire fight with NO tine out cards!

It's obvious that the E2 maybe soon to be an E1 has some underlying issues, possibly personal that triggered his response without thinking death of a parent, loss of a close friend, etc. or the E2 has started hanging out with the wrong crowd. Immediate action is to have his section leader and him removed from formation and waiting outside your office or desk depending on unit space. Inquire the rest of the formation if they are aware of anything happening recently to the E2, if they do not wish to share they can tell you after formation. Get the facts but unless it is over whelming issue as above UCMJ punishment should be pursued it may stop at a Disciplinary Review Board depending on your Service. The E-2 would also be giving an apology to the formation for breaking down the chain of command and why to important to follow orders even when we may not like them. Also he will not take away from the sections unit cohesiveness again

Pick a spot 1 foot behind said shit stain. Destroy everything between you and said spot.

What... Are you out your mind. Do it private... Thats what I would say...

Wall to wall counseling

Before responding, I have read through many of the responses and agree with most of them. Through my years I have often been handed the shit-bags and several of those same shit-bags crossed over to the dark side (became O's) or promoted to brother chiefs. Being a leader means being creative with enforcing our orders and grabbing "Johnny's" attention that will make him/her understand that "if you're gonna be dumb; you've gotta be strong." Something like this would possibly mean constant supervision by myself, the the squad leader, and the team leader working in shifts while Johnny/Jane stands at attention on the footsteps under the flagpole (just an example) until the three of us get tired....that could take a long time, because we would simply be ensuring that we give a few sips of water every hour or so because we don't want Little Johnny/Jane to dehydrate while I am propped up against a tree. Every situation is different, leadership works both ways; know your troops and make damn sure they know you and your (and the service in-which you serve) expectations. You are the leader and it is your job to develop that shit-bag into a future leader. If you don't take the time to develop and guide future leaders in your shadow someone with a smaller shadow, lesser principles and skills will. Remember we can not throw them all out. God knows that I had great chiefs and petty-officers who saw something in me and took the time to put me on the right path. 10% of our troops take 90% of our time, while 90% of our troops only takes 10%.

Karate chop to the throat! GS....

You shut him down first so others do not think they can do the same thing. Then take him or her to private quarters to fi d out what the problem is before punishment is handed out. Anything could have happened. The E-2 should have shown more respect for the E-5 and the situation at hand. That was the wrong way to go about it. I went 3 month in the Navy without a paycheck because of a problem with our disbursing office on the carrier I was on. I told my Senior Chief in private that I quit, until I had a chance to talk to our Captain, and that was after I went through my chain of command with no results. I ended up in Captains Mast for insubordination. Once the commanding officer found out what had happened, heads started to roll. There is a right way and a wrong way to do things. As long as respect is used, and the chain of command is utilized, then you can get things done. But always be respectful.

can ya smell the smoke a coming................he would be so tired at the end of the day....possibly the next day too
get over the kinder gentler army crap....................i sure as hell hope mad dog corrects this shit ...pc is BS and troops doing that i would be lucky not to lose rank over that one

Make sure that they will regret their shotgun mouth overloading their BB ass. Counseling Statements, extra duty, peer pressure, and some extra PT lead by myself.