Important matters of international security aren't usually what sitting presidents discuss with 8-year-old girls.
But on a fall day in 1961, John Kennedy felt compelled to do just that after receiving a letter written in pencil. It was sent by Michelle Rochon, a third-grader living in Marine City, Michigan, a 4,000-person town near the state's southeastern border with Canada.
Michelle's parents frequently discussed current events with her. The height of the Cold War was nearing, and Americans were wary of what the Soviet Union was about to do next. Kennedy was advising families to build nuclear fallout shelters in case of an atomic event. That possibility became all too real in October, when news spread that the Soviets were planning to test the world's largest nuclear weapon over the Arctic.
Michelle heard her parents mention this development one evening at the dinner table. Immediately, she realized what the consequences of such an event would be.
"I thought well, Santa Claus," she recalled to "Good Morning America" in 2007. "And so I ran, sat down at the footstool and wrote the letter."
"Dear Mr. Kennedy, Please stop the Russians from bombing the North pole," she wrote. "Because they will kill Santa Claus. I am 8 years old. I am in the 3rd grade at Holy Cross School."
She took the letter to her neighborhood mailbox, addressed only to "President Kennedy; Washington, D.C."
The envelope made its way to the White House. And on Oct. 28, Kennedy crafted an urgent reply.
"Dear Michelle," the commander in chief began. "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."
Kennedy was into Christmas: Each year, his family gave each other oranges and walnuts as presents, a tradition with disputed origins. It was first lady Jackie Kennedy who would begin the tradition of choosing a theme for the White House Christmas tree later that year, when she dressed the tree in ornaments representing the "Nutcracker" ballet. Their daughter, Caroline, loved Christmas so much, she grew up to write a book about it.
JFK once said of the holiday, "For uncounted millions, Christmas expresses the deepest hopes for a world of peace where love rather than mistrust will flourish between neighbors."
The president, too, had an interest in assuring the safety of Rudolph - and the rest of the world.
"I share your concern about the atmospheric testing of the Soviet Union," his letter continued, "not only for the North Pole but for countries throughout the world; not only for Santa Claus but for people throughout the world."
Luckily, being the leader of the free world comes with certain privileges. Evidently, one of them is a direct line to the Kringle residence.
"You must not worry about Santa Claus," Kennedy assured Michelle. "I talked with him yesterday and he is fine. He will be making his rounds again this Christmas."
He signed the letter "Sincerely, John Kennedy."
It was mailed back to Michigan, and a carbon copy was preserved in the president's papers. The John F. Kennedy Presidential Library and Museum in Boston showcases the letter around Christmas each year.
The original quickly turned 8-year-old Michelle into a national sensation. She was interviewed by the Associated Press and other outlets.
"Michelle told newsmen she was happy to get the President's letter and felt better about Santa Claus," the wire service reported.
But two days after Kennedy wrote his letter, the hydrogen bomb Michelle had heard her parents discussing - known as the "Tsar Bomba" or "King of Bombs" in Russian - was detonated.
In an effort to showcase the power of the Soviet's arsenal, the bomb was dropped over Novaya Zemlya, a remote group of islands in the Arctic Ocean. It weighed 59,525 pounds and was 26 feet long. The resulting blast - which shattered windows as far away as Norway and Finland - was 1,570 times more powerful that the nuclear weapons dropped on Hiroshima and Nagasaki combined, according to the Atomic Heritage Foundation.
The event is still considered to be the most powerful man-made explosion in history.
Kennedy and other world leaders were quick to condemn the testing. They did not, in their official proclamations, however, give an update on the fate of Santa.
But that year, Christmas came as usual in Michigan. Michelle, now known as Michelle Phillips, told the Boston Globe in 2014 that she received letters from Santa Clauses around the world, thanking her for her concern.
"I don't know why it didn't hit me that there were all these different Santa Clauses. I just figured it was all the one Santa Claus," she said. "I had proof there was a Santa Claus. The United States told me they talked to Santa Claus, and he was fine."
It appears Santa made his way to the Kennedy residence, too. The family spent the holiday in Palm Beach, Florida, each year. On Christmas Day 1961, 4-year-old Caroline received a dress, a rocking horse and a trampoline for the White House lawn.