Should we be afraid?
In regards to how safe the U.S. is, each state has an emergency plan that entails mobilizing first responders, providing urgent refuge for evacuation, and decontaminating radiation-exposed people.
A disaster that no one is prepared for is the case in which Putin decides to send a nuclear bomb in our country. With the U.S. being part of NATO, this implies the start of World War III, and in the hypothetical situation in which both countries decide to use all their nuclear power, could even result in the end of humanity. Luckily, that is very unlikely to happen, but that doesn’t mean that the possible danger has been excluded.