Pope Leo to meet with US's top diplomat amidst tensions

US Secretary of State

Marco Rubio will meet Pope Leo at the Vatican on Thursday, in a potentially fraught encounter as President Donald Trump has continued a series of disparaging attacks on the Catholic leader over the Iran war.

Rubio, who also serves as Trump's national security adviser,

was due to arrive at the Vatican's Apostolic Palace Thursday morning for the visit, the first between the pope and a

Trump cabinet official in nearly a year.

The closed-door meeting is expected to last about a

half-hour, after which Rubio will also meet the Vatican's top

diplomat, Italian Cardinal Pietro Parolin.

Leo, the first US pope, drew Trump's ire after becoming a

firm critic of the US-Israeli war on Iran and the Trump

administration's hardline anti-immigration policies.

The president has kept up an unprecedented series of public

attacks on the pope in recent weeks, drawing a backlash from

Christian leaders across the political spectrum.

On Monday, Trump falsely suggested the pope believed it was

okay for Iran to obtain nuclear weapons and said Leo was

"endangering a lot of Catholics" by opposing the war.

Leo told journalists after the latest attack that he was

spreading the Christian message of peace. The pope also firmly rejected the idea that he supported nuclear weapons, which the Catholic Church teaches are immoral.

"The mission of the Church is to preach the Gospel, to

preach peace," said the pope. "The Church has spoken out for

years against all nuclear arms, on that there is no doubt."