[BBC] – US President Donald Trump has begun a visit to Israel by warning of the threat posed by Iran if it acquires nuclear weapons.

“Iran must never be allowed to possess a nuclear weapon,” he told reporters in Jerusalem, speaking beside Israeli President Reuven Rivlin.

He flew in from Saudi Arabia, a key US ally, where he gave a speech to Arab and Muslim leaders at a summit.

Mr Trump will hold talks with both Israeli and Palestinian leaders.

He has called an Israeli-Palestinian peace agreement “the ultimate deal” but has been vague about what form it should take, saying he prefers to leave it to both sides to decide between them in direct talks.

The two-day visit to Israel forms part of Mr Trump’s first foreign trip as US president.

What else did he say in Jerusalem?

Iran must also “cease its deadly funding, training and equipping of terrorists and militias”, Mr Trump said at President Rivlin’s residence.

In a deal with world powers in 2015, Iran accepted curbs on its nuclear programme in return for tangible economic benefits, and the White House confirmed last month that the deal was still holding.

Iranian President Hassan Rouhani, who was re-elected for a second term last week, championed that deal.

However, US Secretary of State Rex Tillerson has underlined that his country’s policy towards Iran is under full-scale review. Israel, meanwhile, considers Iran a mortal threat.

The American president stressed the bond between his country and Israel, saying: “We are not only long-time friends – we are great allies and partners. We stand together always.”

On the peace process, he said: “Young Israeli and Palestinian children deserve to grow up in safety and to follow their dreams free from the violence that has destroyed so many lives.”

After leaving President Rivlin’s residence, he visited the Church of the Holy Sepulchre where, according to Christian tradition, Jesus was buried and resurrected.

What is Mr Trump’s position on Israel’s settlements?

The US president has been widely seen as considerably more supportive of Israel than his predecessor, Barack Obama. He has taken a softer position on the contentious issue of Israeli settlements, suggesting that their expansion rather than their presence might hamper the search for peace.

More than 600,000 Jews live in about 140 settlements built since Israel’s 1967 occupation of the West Bank and East Jerusalem, land Palestinians claim for a future state.

The settlements are considered illegal under international law, though Israel disputes this.

An embassy in Jerusalem?

The president has also sent mixed signals on the issue of Jerusalem, pledging to move the US embassy there from Tel Aviv, angering Palestinians and delighting Israelis.

However he has since stalled, with Secretary of State Rex Tillerson recently telling NBC News that Mr Trump was weighing it up.Israel regards the whole of Jerusalem as its capital, while the Palestinians claim the east as their capital. The international community does not recognise Israeli sovereignty over Jerusalem and countries maintain their embassies in Tel Aviv.