I launched a thermonuclear warhead from a submarine onto a coastal city. The city was entirely destroyed and the area was contaminated. A few turns later, I moved a modern armor into the city to capture it, and chose to keep the city. After choosing to keep a city, you must then choose production for that city before you can end your turn. However, every single production option (including projects) is disabled. Some say the necessary district needs to be repaired first, others say it is contaminated. There isn't any option to skip the production, so my game is over.