Complex sentence: They also needed military contracts to survive and relished the technical challenges of this sort of work, but as early as 1958 Russell and Sigurd expressed regret for their involvement in the development of weapons of mass destruction.
Split into simpler sentences: They also needed military contracts to survive and relished the technical challenges of this sort of work. As early as 1958 Russell and Sigurd expressed regret for their involvement in the development of weapons of mass destruction.