Pope Leo XIV has warned that the world should not give into "a heightened level of conflict on the global level", at the start of his foreign trip in Turkey.

"The future of humanity is at stake, said the Pope, urging President Recep Tayyip Erdogan to act as a source of stability because of the need to promote dialogue and stability.

The Pope will mark a historic Christian anniversary during his visit to Turkey, before heading to Lebanon days after Israeli airstrikes on its capital, Beirut.

The visits had been planned by late Pope Francis, but their main theme of building bridges was embraced by Pope Leo from the moment he stepped on the balcony of St Peter's Basilica after his election in May.

Leo warned that today's wars were like a "third world war fought piecemeal", repeating a phrase that his predecessor had himself used several times, referring to conflicts in Ukraine, Syria, Myanmar and elsewhere.

Since he became pontiff six months ago, he has conveyed a sense of being extremely measured, even cautious. But on this trip, his powers of diplomacy will be closely scrutinised.

A key moment of the trip will take place in the Turkish town of Iznik, the site of the ancient city of Nicaea. Pope Leo and leaders of other Christian traditions will gather to mark the anniversary of an ancient council that took place there 1,700 years ago. In 325 AD, among other key decisions, more than 200 bishops at the council affirmed the belief that Jesus was the son of God, eventually leading to what is known as the Nicene Creed.

Eastern and Western branches of Christianity later dramatically split, but during this trip there will be messages of togetherness and healing divisions.

In Turkey the Pope will also visit the Blue Mosque, as both his immediate predecessors Pope Francis and Pope Benedict XVI had done. He will have meetings with other religious leaders in a gesture of inter-religious dialogue before flying on to the second leg of the trip.

The Vatican says plans for the Pope's visit to Lebanon have not changed following the Israeli airstrikes on Beirut earlier in the week.

He will meet more faith leaders and hear from young people in Lebanon, his visit giving a boost in particular to the estimated third of the country that is Christian.

On the final day of the trip, Pope Leo will celebrate Mass at the Beirut waterfront at the site of the 2020 port explosion, praying for the more than 200 people who were killed and 7,000 others injured.

Over recent months, though he has spoken out on some issues dear to him such as the dignity of migrants, he has certainly not been as overtly political as his predecessor could be.

He has walked such a fine line that in some cases both progressives and traditionalists within the Catholic Church have made the case that he supports their school of thought.

It was for similar reasons that cardinals of different persuasions were thought to have coalesced around him at conclave.

Pope Francis was seen as a visionary but one who was not overly worried about creating consensus, leaving behind a somewhat divided Church. Pope Leo has so far operated very differently, gently holding on to some of the progressive ideals of his predecessor while paying heed to the views of traditionalists.

He has repeatedly called for an end to war, but in a different way to Pope Francis, who memorably made daily calls to the Holy Family Church in Gaza to offer his support.

In meetings on this trip - with Turkish President Recep Tayyip Erdogan and Lebanese civic leaders - Pope Leo may be drawn to comment on his views on conflict in the region.

We may hear something of his impressions at the end of his trip, as it is customary for the Pope to hold a news conference with travelling press on the return flight to Rome.

What we will hear more of this trip is a pope speaking in a Chicagoan accent.

Although Pope Leo, who speaks several languages fluently, has mainly given public addresses in Italian up to this point, the Vatican has confirmed that he will speak English throughout the Turkish leg of his trip, with some French too during his time in Lebanon.