This Island Earth (1955)
Douglas Spencer: The Monitor
The Monitor : Then you know that shortly we can expect Zagon to commence and sustain an all-out attack. Our ionization layer must be maintained until our relocation is effected.
Dr. Cal Meacham : Relocation? To where?
The Monitor : To your Earth.
Exeter : A peaceful relocation. We hope to live in harmony with the citizens of your Earth.
Dr. Ruth Adams : In harmony!
The Monitor : Our knowledge and weapons would make us your superiors, naturally.
Dr. Cal Meacham : Then why haven't your "superior" brains solved the problem of synthesizing uranium?