Edward Teller: 1908 - 2003. Credit: © Lawrence Livermore National Laboratory

Edward Teller, the 'father of the H-bomb', has died aged 95.

Teller was one of the most controversial figures to emerge from the US nuclear-weapons programme instigated during the Second World War. He worked alongside scientists such as Robert Oppenheimer, Enrico Fermi and Richard Feynman on the Manhattan Project, which developed the US atom bombs dropped on the Japanese cities of Hiroshima and Nagasaki.

But whereas some of these figures, notably Oppenheimer, subsequently called for international collaboration on nuclear-arms control, Teller strongly supported a policy of unilateral weapons research. In the 1980s, during Ronald Reagan's administration, he advocated the Strategic Defense Initiative, commonly known as Star Wars, for intercepting nuclear missiles.

The first atomic bombs, such those used against Japan, exploited the energy released by the splitting or fission of the heavy elements uranium and plutonium. Teller realized that even more explosive power would be released by the nuclear fusion of light elements such as hydrogen - the process that powers the Sun.

His research and championing of this notion led directly to the creation of the hydrogen bomb, or H-bomb, first tested on the Pacific atoll of Eniwetok in 1952.

Early years

Born in Budapest in 1908, Teller was a Jewish Hungarian émigré. In the 1930s he studied physics in Germany alongside Werner Heisenberg, who later worked on Hitler's failed attempt to develop an atom bomb. Teller fled the Nazi regime in 1934 along with other scientific luminaries such as John von Neumann and Eugene Wigner.

Teller's experiences of fascism in pre-war Hungary and Germany gave him a lifelong dread of totalitarianism, which motivated his Cold War stance. He once said: "No one could have had a greater influence on me than Hitler, who made it entirely clear to me that one could not ignore politics, and very particularly one could not ignore the worst evils in politics."

Strikingly, Teller's counterpart Andrei Sakharov, who developed an H-bomb for the Soviet Union, became a campaigner against nuclear weapons and called for reconciliation of East and West.

Teller influenced the defence policies of several US presidents. In the 1950s he testified against his former colleague and boss Oppenheimer in the McCarthy trials, causing Oppenheimer to lose his security clearance.

Teller died on Tuesday, following a stroke at his home in Stanford, California.