STANFORD, CALIF. ? Edward Teller, who played a key role in U.S. defense and energy policies for more than half a century and was dubbed the “father of the H-bomb” for his enthusiastic pursuit of the powerful weapon, died Tuesday. He was 95.

Teller suffered a stroke and died at his home on the Stanford University campus, not far from the Hoover Institute where he served as a senior research fellow, said Susan Houghton, a spokeswoman for the laboratory.

Teller exerted a profound influence on America’s defense and energy policies, championing the development of the atomic and hydrogen bombs, nuclear power and the Strategic Defense Initiative.

Teller’s staunch support for defense stemmed in part from two events that shaped his dark, distrustful view of world affairs — the 1919 communist revolution in his native Hungary and the rise of Nazism while he lived in Germany in the early 1930s.

Even the end of the Cold War did not change Teller’s view that the United States needed a strong defense.

“The danger for ballistic missiles in the hands of 18 different nations has increased, and will increase, unless we have a defense,” he said. “If we want to have stable, peaceful conditions, defense against sudden attack by rockets is more needed than ever.”

Witty and personable, Teller nevertheless was a persuasive Cold Warrior who influenced presidents of both parties.

In 1939, he was one of three scientists who encouraged Einstein to alert President Franklin Roosevelt that the power of nuclear fission — the splitting of an atom’s nucleus — could be tapped to create a devastating new weapon.

Two years later, even before the first atom bomb was completed, fellow scientist Enrico Fermi suggested that nuclear fusion — fusing rather than splitting nuclei — might be used for an even more destructive explosive, the hydrogen bomb.

Teller’s enthusiasm and pursuit of such a bomb — he called it the “Super” — won him the title “father of the H-bomb,” a characterization he said he hated. The first megaton H-bomb was exploded in 1952.

The H-bomb was never used in war, but atom bombs were dropped on Hiroshima and Nagasaki, Japan, in August 1945, quickly leading to Japan’s surrender.

In 1995, Teller looked back a half-century and wondered if the United States could have showed Japan the tremendous power of the bombs without destroying the cities. “I think we shared the opportunity and the duty, which we did not pursue, to find … a possibility to demonstrate” the bomb, Teller said at a 50th-anniversary forum. “Now in retrospect I have a regret.”

Still, he defended the existence of atomic weapons, saying, “The second half of the century has been incomparably more peaceful than the first, simply by putting power into the hands of those people who wanted peace.”

Among honors he received were the Albert Einstein Award, the Enrico Fermi Award and the National Medal of Science and, in July, the Presidential Medal of Freedom.