Overkill

Overkill is a term for the use of excessive force that seems to go further than just achieving its goal. For example, trying to kill a duck with a rocket launcher would be overkill.
The term was probably coined in the 1940s and was in common use during cold war era, referring to the arms race between the USA and the USSR. Both nations possessed (and still possess) more than enough nuclear weapons to destroy one another - nuclear overkill.

• Destructive nuclear capacity exceeding the amount needed to destroy an enemy.
• Excessive killing.
• An excess of what is necessary or appropriate for a particular end: “government overkill in dealing with dissent” (Jesse Unruh).
• Mutually Assured Destruction (MAD) is another term used in regards to overkill. For example, if the USA was to detonate a weapon on the USSR soil, it was considered a mutual destruction for both countries, for the USSR would have already launched a nuclear volley of their own, prior to their annhilation.