This article has been updated.

On the eve of U.S. Secretary of State Marco Rubio’s visit to the Vatican on May 7—a visit  widely seen in Rome as an attempt to restore more tranquil relations with the White House—President Donald J. Trump publicly attacked Pope Leo, alleging that “he’s endangering a lot of Catholics and a lot of people” and falsely claiming yet again that for the pontiff, “it’s O.K. for Iran to have a nuclear weapon.”

His latest attack came on “The Hugh Hewitt Show” when the host told the president, who is going to China on May 14-15, that he wanted the pope to talk about Jimmy Lai, the imprisoned Hong Kong Catholic businessman and democracy activist, and for Mr. Trump “to bring him home.” Mr. Trump responded: “The pope would rather talk about the fact that it’s O.K. for Iran to have a nuclear weapon. I don’t think that’s very good. I think he’s endangering a lot of Catholics and a lot of people, but I guess, if it’s up to the pope, he thinks it’s just fine for Iran to have a nuclear weapon.” Mr. Hewitt commented, “He’s from Chicago; he’s got to learn a few things.” 

Before returning to Rome from Castel Gandolfo on Tuesday, Pope Leo responded to journalists about President Trump’s attack but without mentioning his name. 

“The church’s mission is to preach the Gospel and peace. If anyone wants to criticize me for proclaiming the Gospel, let them do so,” the pope said.

“I have spoken about this from the very moment I was elected, and now we are nearing the anniversary. I said [then], “Peace be with you.” 

“The church’s mission is to preach the Gospel, to preach peace,” he repeated.

“If anyone wants to criticize me for proclaiming the Gospel, let them do so with the truth,” he said. Then alluding to the fact that Trump had accused him of being in favor of Iran having nuclear weapons—a false charge—Pope Leo said: “For years, the church has spoken out against all nuclear weapons, so there is no doubt about that. And so I simply hope to be heard for the sake of the value of God’s words.”

For his part, Mr. Rubio downplayed the rift between President Trump and Pope Leo over Iran, saying that Mr. Trump’s recent criticisms were rooted in his opposition to Iran potentially obtaining a nuclear weapon, which he said could be used against millions of Catholics and other Christians. Mr. Rubio said the whole world should be opposed to that.

Mr. Trump “doesn’t understand why anybody—leave aside the pope, the president and I, for that matter—[I] think most people cannot understand why anyone would think that it’s a good idea for Iran to ever have a nuclear weapon,” Mr. Rubio told reporters at the White House.

President Trump openly denigrated Pope Leo for the first time on Truth Social shortly after the airing of a segment on CBS’s “60 Minutes” on the evening of April 12, which featured three American cardinals—Blase Cupich, Robert McElroy and Joseph Tobin—who came out strongly against the war by Israel and the United States against Iran, calling it ‘unjust.” 

Mr. Trump did not strike out against the cardinals; instead, he publicly disparaged Leo, decrying the pope as “weak on crime” and “terrible on foreign policy.” His attack came hours before Leo set out on a visit to four African countries on the morning of April 13. 

On the plane to Algeria, in response to journalists’ questions, Pope Leo said, “I have no fear neither of the Trump administration nor speaking out loudly of the message of the Gospel, which is what I believe I am here to do, what the church is here to do.” 

On another occasion, Mr. Trump falsely accused Leo of being in favor of a nuclear-armed Iran, ignoring the fact that the American-born pope, like his predecessors, is for the total abolition of nuclear weapons. Pope Francis declared that not only is the use of nuclear arms immoral but also the possession of such weapons. Today, nine states have nuclear weapons: the United States, Russia, China, France, the United Kingdom, India, Pakistan, North Korea and Israel.

When President Trump threatened to wipe out the “whole civilization” of Iran, Pope Leo on April 7 denounced this threat against the Iranian people as “truly unacceptable” and called on the citizens of the countries involved in the war in Iran “to contact the authorities, political leaders, congressmen—to ask them, tell them, to work for peace and to reject war always.” Moreover, during his visit to Africa, he stated that he “cannot be in favor of war” and said he was not interested in engaging in a debate with Mr. Trump.

Mr. Rubio, a Catholic of Cuban descent, will be received by Pope Leo in a private audience on May 7. The Vatican confirmed this on May 4 and said the meeting would begin at 11:30 a.m. and end at noon. Mr. Rubio and Vice President JD Vance first met Leo on May 19, the day after the formal inauguration of the Petrine ministry of the first American pope. On that occasion, Mr. Vance handed the pope a letter from President Trump inviting him to visit the United States. 

Mr. Rubio is the first high-level official from the Trump administration to meet the pope since that May 19 meeting, and there have been major differences between the Holy See and the U.S. administration on domestic and foreign policy issues since then, many of which the pope alluded to in his Jan. 9 speech to the diplomatic corps accredited to the Holy See. 

Those tensions are wide-ranging and extend from major differences over the Trump administration’s sidelining of multilateralism, its breaches of international law, the mass deportation of migrants, the gutting of the U.S. Agency for International Development, the wars in the Middle East, the crisis between the Trump administration and the European Union over Ukraine and Iran and much else. 

In addition, there is the quite extraordinary fact that President Trump has not spoken by phone with the pope since Leo’s election on May 8, 2025, almost exactly one year ago. But he has invited the pope’s brother Louis, whom the president described as “all MAGA,” to the White House. Moreover, he even claimed that then-Cardinal Robert Prevost was elected pope only because Donald J. Trump was president.

This and much more constitute the background to Mr. Rubio’s important conversations with Pope Leo and his senior advisors when he visits the Vatican Thursday morning. 

Mr. Rubio, who appears to have been in favor of the war against Iran and for regime change in Cuba, is also expected to have conversations with Cardinal Pietro Parolin, the secretary of state, and Archbishop Paul Gallagher, the secretary for relations with states and international organizations, commonly known as the Vatican’s foreign minister. 

Earlier, the U.S. State Department announced that “Secretary Rubio will meet with Holy See leadership to discuss the situation in the Middle East and mutual interests in the Western Hemisphere.” His visit also aims “to advance bilateral relations with the Vatican and Italy.” The State Department also announced that Mr. Rubio would have “meetings with Italian counterparts” that “will be focused on shared security interests and strategic alignment.”

The Italian news agency ANSA reported that when asked today by journalists about Mr. Trump’s latest attack on the pope, Cardinal Parolin said: “The pope has already responded; I wouldn’t add anything. He gave a very, very Christian response, saying that he is doing what his role requires, which is to preach peace. Whether this is liked or not is another matter.” He added, “We understand that not everyone is on the same page; but let’s say that this is the pope’s response.” 

“Even in the face of these new attacks, I don’t know if the pope will respond,” the cardinal said, but “the line remains the same” as what Leo told the press on April 13.