Upshot–Knothole Encore was a nuclear weapons test conducted by the United States as part of Operation Upshot–Knothole.

[2] As Encore was an effects test, multiple objects were subjected to the blast, including trees.

Since the Nevada Test Site sits in a desert and does not contain trees, the United States Forest Service transported 145 Ponderosa pines from a nearby canyon to Area 5.

The initial release of thermal radiation ignited many of the trees, and the subsequent blast wave blew them over.

In addition to this, six hundred high-ranking personnel and congressmen were on hand to view the exercises, which were aimed to "indoctrinate troops in atomic weapons in order that they will know how to protect themselves and their equipment in event of an enemy atomic attack in combat situations".