Domestic strategies for the Swiss energy system are likely to be affected by a range of uncertain global challenges, such as natural resource availability and depletion, international climate change policies, and global technology policies. We analyze technological choices for Switzerland under a stringent global climate policy with modest global energy resources; and the possible consequences of different global or regional policies in response to the recent nuclear accident in Fukushima, Japan. We use MERGE, an integrated assessment model, with a division of the world in 10 regions, including Switzerland and Japan. We find that nuclear energy, including light water reactors or more advanced technologies have the potential to play a major role in the future energy system. The consequences of a moratorium on the construction of new nuclear power plants include the need for additional electricity efficiency measures and the integration of a large share of intermittent renewables, raising additional challenges.