Around 75,000 people have signed an open letter warning about the threat of civil war in France.
The message, published in a right-wing magazine, accuses the French government of granting "concessions" to Islamism.
"It is about the survival of our country," said the text, which was issued anonymously by soldiers before being backed by members of the public.
The French government condemned a similar letter published by semi-retired generals late last month.
The minister in charge of the armed forces, Florence Parly, said at the time that they would be punished for defying a law that forbids reservists or serving members of the military from expressing opinions in public on religion and politics.
However, far-right leader Marine Le Pen, a candidate in next year's presidential election, spoke out in support of the estimated 1,000 servicemen and women who backed the letter.