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

I would make him do drills and make his life a living hell and he would learn to respect commanding officer.

Report it to the Chief Petty Officer on Duty at the time.

There is a job to be done, you are training for the job, the training is tough because the job is tough, the training is making you tough, so you can preform the job.
Sometimes people don't like doing what needs to be done, but it has to be done.

I would do it in the same manner as it was shown to me back in the 70s. Take him out to the wood-line and show him the error of his ways

The drill instructors build on what the parents instill. Today we have a softer weaker generation. The threat of NJP takes away the tools we need as leaders. Thrash his assistant until he can't get up. Break his mind until he's nothing. Build him back up tough. In the mean time he's on every shot detail you can throw his way. To bad we can't beat people any more. It's the corps. We are not supposed to be soft. Mouths like that get people killed in combat.

i would remind him of what he should have learned in boot camp about lawful and direct orders explain to him clearly how the army works , no matter how insufficient a task might seem the directive to carry out an order must be followed,because the Army works as a team ,,the lives of others and the mission ,may rely upon him to understand and follow orders.and also to carry out those orders to the best of his ability., Ask him again if he clearly understands this. If he does, reassign the task to him Establish immediate remedial punishment for his insubordination " besides the task set forth, and if that works fine, you do not have to carry this matter out any further,

The fix is simple. Document on formal counseling and assigned corrective training which fits the inappropriate behavior until default workable attitude is obtained. If not, continue further counseling and forward to chain for chapter process out on failure to adapt because defective soldiers drain the purpose of the mission and valuable time from the nco which keeps them away from training a squad or platoon for war.

Request 50 push ups

I would then tell him he has now just volunteered to do that task every day until he understands to a where he went wrong talking back to a senior NCO or until he transfer out of your unit. Too bad we can't just take him out back and give him some one on one training like in the old days.

My Father was a Gunnery Sergeant in the United States Marine Corps. I would do as my Father done me and slap the shit out of him before he finished his sentence.

Give to someone else and give him a more shitty detail again and again and again until he's had enough and give it to him again . Eventually have a face to face to find out what his problem is with taking orders .

Calmly explain to the private how failing to follow a legal command by an NCO can lead to disciplinary actions on the U.C.M.J. and then smoke his ass in the yard until the remaining soldiers complete the daily duties. Both should drive discipline into the Private without having to go the article 15 route.

Gunny has it right

I really hate to say this, but this issue depends on which era of Leaders you are talking about. In my Old School Military Experiences, there would be no tolerance at all regarding insubordination of any kind. Today though, a Superior has to weigh his reaction with the Modern Adopted Rules and Regulations to keep from ending or destroying their Careers!!! It's probably good I retired when I did. No Offense Intended with today's Leaders but I'm Old School Military and my Watch is over as I Stood Relieved in 2002! Doc Bradshaw

The foolish young troop will not only do the assigned task today but for the next week or until I'm convinced they have figured out where they fit in the BIG machine! I had this happen with a work detail ONCE! We had 25-30 double doors with brass knobs and large cover plates on both sides. Over the next 2 weeks she polished all of them! From then on I was known to the work details that came to our building as "Sgt. Brass"!

Step into my office PRIVATE!!! Leave no identifying marks when he crawls back out!!!

Place the E2 in charge of the formation and take them all out for Physical Training (all day)

As the senior Sgt, i would have taken the Pvt and his Sq Ldr into the office . First the sqd ldr and informed him that he will MAKE sure Pvt never pulles this mess again. Then bring in Pvt and inform him that he has shown disrepect and disobeyed a lawful order from a NCO. Then ask Pvt do u want to continue in the service? His answer will dictacte if he stay's or goes.

I know this isn't a correct response in this day and age of the military but this cat would find my size 5.5 wife so far up his ass the water on my knee would quench his thirst..and he would forever be on shit detail until he learned...

Push ups till the world changes direction or office hours and all kinds of extra duty