TRUE

Temperatures at the core of a thermonuclear weapon's secondary stage, which involves nuclear fusion, reach approximately 100 million degrees Celsius. This extreme heat is a physical requirement to overcome the electrostatic repulsion between atomic nuclei, allowing them to fuse and release energy (Atomic Archive). While early fission-only weapons reached temperatures in the range of several million degrees, modern multi-stage weapons achieve temperatures between 100 million and 300 million degrees Celsius at their center (NCBI). These conditions significantly exceed the temperature at the core of the Sun, which is approximately 15 million degrees Celsius (Forbes). Official scientific documentation from the Department of Energy and fusion research entities like EUROfusion confirm that 100 million degrees is the standard benchmark for initiating the deuterium-tritium fusion reactions used in the final stages of such weapons.