Norwegian resistance fighter Joachim Ronneberg, whose bravery helped keep Nazi Germany from building nuclear weapons, has died at 99.



Norwegian Prime Minister Erna Solberg called him one of the country's heroes and possibly the last of the World War II resistance fighters.



Ronneberg fled Norway when the Nazis invaded in 1940. He trained with the Norwegian resistance in Britain and returned behind enemy lines.



Ronneberg led Operation Gunnerside -- the 1943 secret mission that blew up a German plant producing heavy water, a necessary component in early nuclear research.



The Nazis were working on building nuclear weapons and may have developed a bomb to use on New York or London if the plant had not been destroyed and Hitler defeated in 1945.



Ronneberg's story was dramatized in the 1965 film The Heroes of Telemark.



Ronneberg later became a journalist and rarely talked about his wartime experiences except to warn younger generations of the dangers of totalitarian governments.

