Pope Francis revealed on Sunday for the first time in an interview that he had signed a resignation letter nearly a decade ago should poor health prevent him from carrying out his duties.

Francis — who turned 86 on Saturday — said in the past that he would step down from the papacy should health problems keep him from his duties.

The Pontiff told ABC newspaper that he signed his resignation letter and handed it over to the Vatican’s secretary of state, Tarcisio Bertone, before that cardinal’s retirement in 2013.

"I signed the resignation and I told him, ‘In case of medical impediment or whatever, here’s my resignation. You have it,'" the Pope said.

Asked by the interviewer whether he wanted that fact to be known, Francis replied, "That’s why I’m telling you," adding that he didn’t know what Bertone subsequently did with the letter.

Francis has been limited in his ability to walk by an inoperable knee condition, which has forced him to rely on a wheelchair in recent months.

The Pope has had to cancel or reduce activities several times over the past year because of pain, and in an interview in July, he acknowledged that he needed to slow down.

"I think that at my age and with this limitation, I have to save myself a little bit to be able to serve the Church. Or, alternatively, to think about the possibility of stepping aside," he indicated.

Francis’ predecessor, Benedict XVI, quit over failing health in 2013. He now lives in Vatican City.

Pope calls conflict in Ukraine "world war"

In a separate context, Francis considered that the conflict in Ukraine is a "world war" and will not end soon.

"Now [Ukrainian President] Volodymyr Zelensky is sending one of his religious advisers to me for the third time," the pontiff said, adding that "I'm in touch, accepting, helping."

"I don't see the end [of the conflict] in the short term, because this is a world war," he said, pointing out that "there are already several hands involved in the war."

"There are many interests," he concluded.

It is noteworthy that in an extract from his new book, Pope Francis stated that reforming the United Nations was "more than obvious" and that the war in Ukraine exposed the UN's limitations.

The Argentine pontiff indicated that the war in Ukraine highlighted the need to ensure the current multilateral structure -- especially the UN Security Council -- finds "more agile and effective ways of resolving conflicts."

According to the Pope, the organization was founded to prevent the horrors of two World Wars from reoccurring, but while the threat represented by those conflicts remained, "today's world is no longer the same."

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