### Instruction:
What is the B61 nuclear bomb?

### Input:
The B61 nuclear bomb is the primary thermonuclear gravity bomb in the United States Enduring Stockpile following the end of the Cold War. It is a low to intermediate-yield strategic and tactical nuclear weapon featuring a two-stage radiation implosion design.

### Response:
The B61 nuclear bomb is a low to intermediate yield strategic and tactical nuclear weapon. It features a two-stage radiation implosion design, and is the primary thermonuclear gravity bomb in the United States Enduring stockpile following the end of the Cold War.