Julia's explanation

 

In some ways she was far more acute than Winston, and far less susceptible to Party propaganda. Once when he happened ... to mention the war against Eurasia, she startled him by saying casually that in her opinion the war was not happening. The rocket bombs which fell daily on London were probably fired by the Government of Oceania itself, "just to keep people frightened." This was an idea that had literally never occurred to him.

— George Orwell, 1984