When a teacher at her primary school in Bristol revealed all, she and her classmates were left in shock.
Lily decided to vent her disappointment by writing a letter to the man himself.
Her spelling may not be perfect but she appears to understand the human cost of the ban better than those imposing it.
"Dear Donald Trump," the Wallscourt Farm Academy pupil begins. "I don't think your president situation is fair.
"Imagine you were in 'Syrrea' and the president didn't let you into America. How would you feel?
"I'm not from 'Syrrea' but (please) try to make the world better. Try to reply soon. From Lily."
After writing the letter, the year 3 pupil took it into school to show her teacher Jon Miller, who she had told the day before that she planned to write a letter.
But not expecting his student to live up to her words, he was left stunned when he received the A4 sheet of paper and smashed it online.