After 9/11 the British govt sent out a booklet to all households explaining how to deal with a terrorist attack (have water and tinned food on hand, stock up on duct-tape to seal windows in case of a gas attack, and so on). That was in 2001, and no-one has really had to use the info.

They sent it out just because people were jittery back then.

It is always a good idea to have some emergency supplies to hand, but I really don't think WW3 is going to start.