In 1961, immediately after overhearing her parents discuss the possibility of Soviet nuclear tests at the North Pole, 8-year-old Michelle Rochon grabbed a pencil and wrote a letter to U.S. President John F. Kennedy, in which she asked him to prevent the tests for one particular reason. To her surprise, Kennedy soon replied.
Dear Mr. Kennedy,
Please stop the Russians from bombing the North Pole because they will kill Santa Claus. I am 8 years old. I am in the third grade at Holy Cross School.
Yours truly,
Michelle Rochon

October 28, 1961
Dear Michelle:
I was glad to get your letter about trying to stop the Russians from bombing the North Pole and risking the life of Santa Claus.
I share your concern about the atmospheric testing of the Soviet Union, not only for the North Pole but for countries throughout the world; not only for Santa Claus but for people throughout the world.
However, you must not worry about Santa Claus. I talked with him yesterday and he is fine. He will be making his rounds again this Christmas.
Sincerely,
[Signed, ‘John F. Kennedy’]
Two days after Kennedy responded to Michelle’s letter, the Soviets tested the Tsar Bomba on Severny Island—it remains the largest, most powerful nuclear weapon ever to have been detonated. The bomb created a fireball with a width of 8km; its blast wave circled Earth three times.
Little known fact. The pilot who dropped the Tsar Bomba was, fittingly, Andre the Giant.
https://en.m.wikipedia.org/wiki/Andrei_Durnovtsev
I hope Santa will still be fine this year. Lovely letter of note.