As 2017 was drawing to a close, the horrors of war and people's yearnings for peace were on Pope Francis' mind and in his prayers.

In an unusual move late Dec. 30, the pope had the Vatican press office and Vatican media distribute a copy of a famous photograph from the aftermath of the atomic bombing of Nagasaki.

The photo shows a young boy, about 10 years old, carrying his dead little brother on his back. The boy is taking his brother to be cremated.

On the back of the card, Pope Francis wrote, "The fruit of war", and signed his name.

Below his signature, the pope explained that the photo was taken by U.S. Marine Corps photographer Joseph Roger O'Donnell. After the bombs were dropped on Hiroshima and Nagasaki in 1945, O'Donnell was assigned to document the scenes.

"The sadness of the child is expressed only by his lips, bitten and oozing blood," the pope wrote.

The Vatican newspaper, L'Osservatore Romano, printed a copy of the photograph and pope's explanation on the back page of its edition for January 1, the Catholic Church's World Peace Day.

And in his first Angelus of 2018, Pope Francis made special reference to the migrants and refugees who are among the victims of war.

"It is precisely these people who are dedicated to the theme of the World Day of Peace that we celebrate today: 'Migrants and refugees: men and women seeking peace', this is the motto of this Day. I would like once again to voice these brothers and sisters who call for a horizon of peace for their future. For this peace, which is the right of all, many of them are willing to risk their lives on a journey that in most cases is long and dangerous," he said.

"Please do not turn off the hope in their hearts; we do not stifle their peace expectations! It is important that everyone, civil institutions, educational, welfare and ecclesial realities are committed to ensuring refugees, migrants and everyone a future of peace. May the Lord grant us to work in this new year with generosity, generosity, to create a more supportive and welcoming world."

The publication of the picture comes as the latest expression of the Pope's continuing concern about the nuclear threat and as North Korean leader Kim Jong Un today in his own New Year's Day address on television warned that the nuclear button on his desk is ready for use if North Korea is threatened. Kim also indicated however that he is open to talks with the south.

It was after a year of mounting international tensions over North Korea's nuclear programme that Pope Francis in November warned that nuclear weapons create a "false sense of security" and serve a "mentality of fear" that affects the entire human race.

He condemned the escalation of the arms race and the price of modernising and developing weaponry and said the result is that "the real priorities" such as the fight against poverty, the promotion of peace, the undertaking of educational, ecological and healthcare projects, and the development of human rights, are relegated to second place "Nor can we fail to be genuinely concerned by the catastrophic humanitarian and environmental effects of any employment of nuclear devices," he added in his address to participants in the international symposium, "Prospects for a World Free from Nuclear Weapons and for Integral Disarmament".