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

It must be nipped in the bud quickly and without hesitation. Having had a few minutes to think about it, here goes....
PFC Shitbird and his team leader stand fast. All others fall out and carry on.

Have PFC Dipshit stand by while I ensure his team leader knows what my expectations are; "Instant obedience to lawful orders. Period. Any other answer is unacceptable. The fact that PFC Dipshit thinks it is okay to open his trap is a direct reflection of your leadership. Take a look at how you are leading and determine how this could happen."

To PFC Dipshit; "If you have decided to end your time in the military you have chosen a sure-fire method. If you do not comply with lawful orders, it will eventually end with you on a bus headed for home. But only after spending the next few weeks/months becoming the example of what not to do. If that is what you want, we will go there. If not, get your ass moving on what you were ordered to do."

Praise in public, punish in private. "You stand fast after formation." Give him a chance to explain insubordination. Mandatory counseling. If he is defiant in private after getting the chance then burn him. ART15. Sometimes people are defiant because something happened and they feel out of control so they try to take it wherever they can no matter how inappropriate. Sometimes a wife cheated or a parent died. Sometimes the hospital calls and congratulates you on having cancer. To outright burn a Joe without gathering the facts is irresponsible and we would want someone breathing down our neck to take that extra moment to consider what might be going on too. If it's nothing more than attitude and a shitty personality then by all means light that dead Christmas tree and know you probably saved lives downrange.

I can speak from experience on this one. On my first boat( yes I'm a submariner) as an E3 I was made Deck Div LPO, AKA Leading Seaman. While passing out the day's job assignments, I was told "f@#k no" by one of the new seaman. I was shocked to say the least. I went to the 1st LT, a TMCS, and informed him of my situation. He told me in no uncertain terms to take said individual to the back of the work barge and show him the error of his ways. I did so, physically. The young man never questioned me again.
Now, before everyone jumps on me, let me give you my opinion on this matter. This was the late '70s. We were still in the Viet Nam mind set. However; when did the military go from being a gung ho military organization to a job? "Ask him what's wrong". Really?! When you're at 400ft and there's a fire in the Torpedo Room, or you're someplace where people are shooting at you are you really going to take no as an answer?? Or are you going to kick him in his ass, and get him motivated to move in the right direction? I spent 20 years in the Submarine Force and I've seen people come and go. And the ones that went were sent haze gray and underway on surface ships. Which, BTW, was the same as failing. Next time someone tells a senior NCO he doesn't want to do something, point out that the contract he signed doesn't say anything about liking it. He (or she) doesn't have to like it. They just have to do it. STS1(SS) USN, Ret

I would definitely find out where the hell that came from, do my counseling, and give him some extra details as corrective action. But then I would step back and look in the mirror. I have noticed being in the mess hall last year that E-1's and E-2's eating with E-5's. During my young Soldier days that we were never allowed to eat with our NCO's and when we did it was a privilege. I am not saying that all NCOs are the same, but we have NCOs trying to be friends. You can't be a friend and lead. They need to know that you care for them but they neef leadership, not friendship. Just the thoughts of an old SGM.

In any command of mine. At that response, he becomes a meritorious Private and gets to know the brig staff.

I don't care if his dog just died and his wife left him. Immediate, intelligent obedience is the only acceptable response to a legal order. Any NCO that accepts less warrants a meritorious demotion. To accept less is an open invitation to misconduct before the enemy.

I had a case where this happened and it turned out the Sgt was sleeping with the Pvts wife. Immediately upon completing the court-martial for the Pvt. We initiated the court martial for the Sgt. They got to be brig mates.

It is far kinder to beat a dog one time hard then a thousand times lightly.

EDIT: I believe someone edited the original question posted by LTJG (Join to see) I'm not sure why. The original question was better and makes the responses not quite as nuanced.

THROAT PUNCH!!!

As a drill sergeant I would have handled this way different. Haha. But now I remain calm and tell them in formation that is fine, no problem, come see me after formation with your squad leader. The magic of the pen is so much stronger than me yelling anymore. This PVT learns really quickly he has made a bad choice. Their time is important to them and when they don't have as much of their time as they used to it usually changes their attitude. And when it doesn't they soon will have all the time they want as a civilian.

I would probably still be in Leavenworth!

I have been in this position only with a specialist (e4) not a pvt. I gave and order for said specialist to perform a work detail. He refused. I pulled him to the side gave the order again. 2nd refusal. By that point I was livid. I asked why. He stated that by right of duty position we were equal and he shouldn't have to do a detail like that when there were other soldiers who could do it. Now I was seeing red. I reminded him that I was a sergeant (e5) and by that fact alone I out ranked him he said he didn't care what my rank was. I then "forcibly" informed him to report to the platoon office and stand by. I calmly reassigned the detail and went to the plt office. No specialist. He had talked with the platoon sergeant; who happened to be his tank commander and said I was singling him out because I knew he was a better soldier than me and he deserved the stripes not me. The platoon Sergeant said that he would handle it. I informed to PSG that I wanted to handle it since it was me that specialist disrespected. He asked what I planned to do. I informed him that I have already counseled that soldier on his attitude towards me before. This time I wanted to push for a summarized Art 15. The PSG said that I had some balls and he didn't think the 1SG or CO would do that to this particular specialist but if I wanted it then go. 1SG agreed commander didn't scared the hell out of the specialist and prevented him before appearing in front of next promotion board because of it. Earned my rep as a no bullsh17 NCO.

If you are a senior E5 and you don't know what to do, maybe you shouldn't be a E5.