"There is more uncertainty around us," Norwegian Justice and Public Security Minister Emilie Mehl told the outlet, adding: "We must take care of the civilian population in the event of a 'worst-case scenario' of war or armed attack. Shelters are one of the protective measures we need."Up until 1998, any new large apartment buildings constructed in Norway were required to incorporate a bomb shelter into their design. No new shelters have been built since, NRK reports."We are now actually setting a requirement that buildings over 1,000 square meters must have shelters," Mehl said.The Norwegian government is proposing two types of shelters — new shelters will meet the requirements of modern designs which protect against chemical, radioactive, as well as high explosives.The second type of shelter will be adapted from existing structures to protect against conventional weapons.