Without Warning is an alternate history novel written by the Australian author John Birmingham.

[3] On the eve of the Iraq War, March 14, 2003, the majority of the population of the contiguous United States (along with the bulk of the populations of Canada, Mexico, and Cuba) disappears as the result of a large energy field that later comes to be known as "The Wave".

Without Warning deals with the international consequences of the disappearance of the world's last superpower on the eve of war.

Birmingham said he was inspired to write the novel after hearing someone during a student demonstration at the University of Queensland say the world would be a better place if the United States disappeared.

Birmingham, the author, said that he did this as a nod to American novelist Stephen King: When I was a kid and started reading big, fat books, the thing that struck me about his novels, so different to the dull, dull things they made us read at school, was they were full of real world references.