Challenge: "USA" stands for "US Army"

[Dr Pervez Hoodbhoy]

Your challenge, chould you choose to accept it, is to have a military coup attempt (its success is at your discretion) in the United States by 1984 with a POD no earlier than the Tet Offensive.

[Ghost 88]

Your challenge, chould you choose to accept it, is to have a military coup attempt (its success is at your discretion) in the United States by 1984 with a POD no earlier than the Tet Offensive.
With these restrictions this belongs in ASB.

[Dr Pervez Hoodbhoy]

With these restrictions this belongs in ASB.

Alright, then it has to be by the present day.

[LordInsane]

Alright, then it has to be by the present day.
That, combined with the fact that it is allowed to fail, makes it unlikely, but not extremely completely unlikely.

[Ghost 88]

Alright, then it has to be by the present day.
The only way to get the US Military to pull a coup, that has any chance of success or near success, is for the Congress and the President to so grievously violate the Constitution, that they would be considered domestic enemies to the oath that every serviceman takes "to support and defend the Constitution from all enemies both foreign and domestic".
For both the Prez and Congress to go this far would take ASBs interference.

Of course some megalomaniac officer might attempt one. However it will get only as far as the first officer or enlisted person with the common sense to say " Drop dead sir".