similar information is in the linked Wikipedia article (accessed today)

https://www.smithsonianmag.com/smart-news/do-you-hear-what-i-hear-conjures-images-of-peace-everywhereand-nuclear-annihilation-180979292/

2021 article by David Kindy

Christmas songs are the standard fare on many radio stations in the days leading up to December 25. Most project the sounds of the season, focusing on nostalgic winters and family fun while others echo the religious nature of the holiday.

One song in particular—“Do You Hear What I Hear?”—resonates with images of love and hope as it retells the story of the Nativity through the eyes of a little lamb. The powerful lyrics include the potent message to “Pray for peace, people, everywhere.”

However, that sacred sentiment belies the nature of the song’s origins: it was born of the fear of nuclear annihilation during the Cuban Missile Crisis in 1962.

Written by husband and wife Noël Regney and Gloria Shayne, “Do You Hear What I Hear?” has a two-fold meaning, reports Reba A. Wissner in the Bulletin of the Atomic Scientists. While the lyric “a star, dancing in the night, with a tail as big as a kite” conjures a heavenly body that guides the Magi to Bethlehem, it also represents an ICBM soaring across the sky.

“The star was meant to be a bomb,” the couple’s daughter Gabrielle Regney told the Curiosity Desk of WGBH FM in a 2019 interview.

Regney’s father wrote the song in October 1962 as the world watched and waited to see what would happen. Following the discovery of intercontinental ballistic missile bases in Cuba, the two world powers stood at the brink of nuclear war. The United States demanded the removal of the missiles from the Communist island only 90 miles from its shores while the Soviet Union refused to back down. Warships from both countries faced each other in a tense standoff.

Amidst this angst, Regney had been asked to compose a song that would be on the flipside of a single record. Born in France, he had been conscripted by the Germans during World War II, but escaped to join the French resistance. Regney’s experience of facing death in a horrible conflict left an emotional mark that he would carry with him throughout his life.

“He had to do some pretty hard things to get himself out of that,” his daughter recalls in the WGBH interview. “Things that I think really much scarred him.”

Per Spencer Kornhaber in a 2015 Atlantic article, Regney was inspired to write the first line of the song—“Said the night wind to the little lamb …”—when he witnessed a scene of peace and innocence on the streets of New York City.

“Enroute to my home, I saw two mothers with their babies in strollers,” Regney recalled later. “The little angels were looking at each other and smiling.”

The lyricist wrote the words and then asked his wife to compose the music. The couple had a string of song-writing hits at the time that were recorded by many popstars, including “Rain, Rain, Go Away,” “Sweet Little Darlin’,” “Goodbye, Cruel World” and “What’s the Use of Crying,” per Douglas Martin in the New York Times in 2002.
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"'I am amazed that people can think they know the song -- and not know it is a prayer for peace,' Mr. Regney said in an interview in The New York Times in 1985. 'But we are so bombarded by sound and our attention spans are so short that we now listen only to catchy beginnings.' "