Project Islero

Project Islero was an attempted Spanish nuclear program. Named after Islero, the bull which felled the famous bullfighter Manolete, the program was created by Generals Agustín Muñoz Grandes and Guillermo Velarde in 1963. Although Spain possessed the second largest uranium deposits in the world at the time, it was not until the Palomares Incident of 1966 that Spain would focus on plutonium-239 implosion-type designs. Yet, in 1966, Franco paused the military research, shifting efforts to nuclear reactor construction and plutonium production. However, the program was resumed in 1971, with help from France to refine the material and fund the nuclear facilities.

Lasting from the middle stages of Francisco Franco's rule into the beginning of the democratic transition, the project was prematurely cancelled due to American pressures in 1981, although it only formally ended in 1987 under Felipe González. Although the project never developed a nuclear weapon, the country possessed the capabilities to both design and manufacture the necessary components, with the Spanish Foreign Minister, José María de Areilza, declaring in 1976 that Spain would be able to manufacture the bomb "in seven or eight years if we set our minds to it."