With Isaak Gurevich, Isaak Pomeranchuk, and Khariton, Zeldovich prepared a scientific report on the feasibility of releasing energy through nuclear fusion triggered by an atomic explosion, and presented it to Igor Kurchatov. Zeldovich had benefitted from physical and technical knowledge provided by German physicist Klaus Fuchs and American physicist Theodore Hall, who each had worked on the American Manhattan Project to develop nuclear weapons.