In the months after Robert Prevost became Pope Leo XIV, in May 2025, he kept a relatively low profile. He fulfilled prescheduled trips to Turkey and Lebanon and released just one pontifical document, on the church’s love for the poor, begun by Pope Francis. But in 2026, Leo has come into his own with biblical messaging against war. At a Mass on January 1, after the Trump administration had killed more than 100 people by attacking boats in international waters in the preceding four months, the pope challenged policies undermining “diplomacy, mediation, and international law.” In an annual address to Vatican-accredited diplomats from 184 countries eight days later, he was even more pointed in his criticism: “War is back in vogue and a zeal for war is spreading.”
The Vatican’s criticism of militaristic policy caught the attention of the U.S. Department of Defense, which summoned the Holy See’s longtime nuncio (ambassador) to the Pentagon in late January. Tensions increased further in April, when American cardinals joined Leo in challenging the morality of war against Iran. Trump crudely assailed the pope on social media, denigrating him as “WEAK on Crime” and “terrible for Foreign Policy.” Vice President JD Vance piled on, attempting to lecture the pope on theology.
But the Trump administration’s attacks on the pope misunderstand not only the Catholic stand on war and the papacy’s opposition to what it sees as unjustified aggression. They also fail to comprehend that the pope, despite being American, is continuing to lead the Catholic Church away from the United States and Europe and toward a multilateral orientation. Unlike Francis, who was pigeonholed as anti-American in part because he was from Argentina and caricatured as overly preoccupied with the poor, Leo has garnered the broad support of U.S. and European bishops. Leo can carry on Francis’s vision of a more global—and more radically compassionate—church while criticizing U.S. foreign policy in a way his predecessor could not. An active American pontiff calling out U.S. actions in colloquial English gives the world an unexpected focal point for pushing back on Trump and forges more unity among American Catholics who were fiercely divided under Francis.
NOT JUST WAR
The pontiff’s frustration with the Trump administration’s foreign policy predates the U.S.-Israeli war on Iran. According to sources in the Vatican diplomatic corps, Leo took issue with Washington’s aggressive deportation of noncriminal immigrants, many of whom are Catholic; the 2025 U.S. national security strategy, which scorned multilateralism; and the military operation to seize Venezuelan President Nicolás Maduro and his wife and whisk them off to the United States. At the time of Maduro’s capture, Vatican officials were negotiating with the U.S. government to resettle the Venezuelan leader in Russia to avoid violence.
Trump’s first outburst against papal politics, in April, ultimately erupted after three U.S. cardinals appeared on the television show 60 Minutes and called the Iran war “unjust”—a theologically loaded word. But the president should not have been surprised by such criticism from the Vatican. The Catholic Church’s “just war” theory, rooted in ideas developed by the philosopher and theologian Saint Augustine, excuses war if it is necessary to restore peace and protect the innocent. War is morally acceptable only if it meets certain criteria. It must have a just cause—that is, to defend a jurisdiction against severe damage. It must be undertaken by a legitimate authority in the name of justice and peace and only as a last resort. And the actions of war must be proportional to the actions that caused it. Any violent engagement should not exceed the damage done by those who provoked it.
Popes have been criticizing U.S. military adventurism since the nineteenth century. Pope Leo XIII, who reigned from 1878 to 1903, protested the U.S. invasion and occupation of the Philippines, which resulted in the destruction of church property; the dismembering of parishes; and the jailing, murdering, and expelling of Spanish priests. Leo XIII—whose landmark 1891 encyclical on capital, labor, and social justice was a driving reason for the current pope to name himself Leo XIV—even issued an apostolic letter condemning “Americanism,” the idea that individual conscience, not doctrine, should guide faith.
Pope John Paul II, who was pontiff from 1978 to 2005, opposed both the 1991 Gulf War and the 2003 invasion of Iraq. In 2003, he sent Cardinal Pio Laghi, an old friend of President George H. W. Bush, to warn his son, then President George W. Bush, that an invasion would result in countless casualties, sectarian conflict between Shiite and Sunni Muslims, and long-term regional turmoil, including the scapegoating and persecution of Christian communities in revenge for the U.S. invasion. George W. Bush was not moved; the president told Laghi that reason—and Jesus—were on his side and were guiding him.
The pope is continuing to lead the Catholic Church away from the United States and Europe.
Pope Leo, a member of the Augustinian religious order, is particularly attuned to Augustine’s ideas about unjust wars. He also developed visceral opposition to ideologically motivated violence from his time in South America. Prevost spent most of his career in Peru: first as a missionary in the 1980s and 1990s, and then as a bishop from 2014 to 2023. In Peru, he confronted acts of terrorism by the leftist guerrilla group the Shining Path as well as incidents of state brutality justified as part of counterinsurgency operations. This experience echoes what Francis, his predecessor, saw as a Jesuit during the so-called Dirty War in Argentina (1974 to 1983), in which the military junta murdered and jailed citizens accused of supporting the political left. When Francis brought Prevost to Rome in 2023 as a surprise pick to lead the Dicastery of Bishops, the office that selects bishops around the world, the two men grew close and met every Saturday to discuss church matters.
The Vatican also has geopolitical and technological concerns about the war. It disapproves of Washington’s propensity for unilateral action and its dismissal of international treaties such as the Paris Climate Agreement and multilateral institutions such as UNESCO and the World Health Organization, which the Vatican actively participates in. And as artificial intelligence becomes part of how countries fight, the Vatican worries that the United States is more willing to go to war because of its technical prowess. Leo is finalizing his first encyclical, to be released on May 25, which will be about technology and human dignity; Vatican observers expect he will insist on an international agreement to curb the risks of AI deployment, including the use of AI-guided weapons against civilians.
GOING GLOBAL
The Vatican’s desire for peace in Iran goes beyond its general commitment to a theory of just wars and opposition to what it sees as unnecessary violence. It is also a commitment to serving a global family. The Vatican works from the premise that where population and faith grow, influence also grows. Leo is accelerating the departure from a Western-centric church, which is increasingly secularized and in demographic decline; in this, he is following the lead of Francis, who observed in 2024 after a trip to Southeast Asia that the church is “still too Eurocentric, or, as they say, ‘Western.’”
Since the Second Vatican Council in the 1960s, which elevated the role of laypeople and encouraged Mass in the vernacular instead of Latin, the Catholic Church has prioritized engagement with the world. Pope Paul VI was the first to embark on international travel. He visited New York to speak at the United Nations to condemn the war in Vietnam, declaring, “Never again war!” (His speech received a ten-minute standing ovation.) He also went to countries in Africa, Asia, and the Middle East, mainly to visit the faithful in those regions. John Paul II traveled to 129 countries, logging a distance equivalent to going to the moon and back three times. Francis emphasized his beloved “peripheries,” trekking to conflict-ridden or more remote locations, where he often initiated dialogue with leaders of other religious faiths. In 2021, the Argentine pope memorably hobbled down the narrow streets of Najaf, Iraq, to meet the most revered Shiite scholar Grand Ayatollah Ali al-Sistani.
Even though Iran is a predominantly Muslim country, the Holy See and Iran have long-standing diplomatic bonds that predate even the Second Vatican Council. The two established bilateral relations in 1954 and maintained them uninterrupted after the Islamic Revolution. They also have a mutual respect for religious texts: the Farsi translation of Augustine’s Confessions, for example, can be found in Iranian bookstores. In parallel with U.S. negotiations on Iran’s nuclear capability in 2014, a delegation of American bishops signed a joint declaration with Iranian seminary teachers outlining shared opposition to weapons of mass destruction. Pope Francis praised the Iran nuclear deal at the United Nations. The Catholic Church in the United States, encouraged by Rome, even lobbied Congress to approve the agreement.
In 2021, Francis sent a Belgian priest of the Franciscan order, Dominique Mathieu, to serve as archbishop of Tehran-Isfahan; in one Francis’s last acts as pope, in 2025, he made Mathieu a cardinal. The only Latin Catholic leader in Iran, Mathieu counts about 2,000 Catholics in his flock among some 200,000 Christians of different denominations. This small number does not mean Rome discounts the community as unimportant; rather, as Leo expressed in a visit to Algeria in April, a country with few Catholics, the community is considered a biblical “salt”—a seasoning that adds flavor and can make an impact even in small quantities—and can be a positive influence for peace when living in fraternity with Muslim neighbors with whom the community has coexisted for centuries.
Having this presence in Iran means the Catholic Church has a local perspective on the current crisis. It increases the pope’s feeling of urgency in speaking up on behalf of those killed, whether or not they are Catholics. The church’s intellectual foundation, especially the natural law tradition, assumes the ability of the church to speak for all people. Iranian parents of children murdered in the bombing of an elementary school on February 28, for example, wrote to the pope to beseech him to be “the voice for our voiceless children” in seeking peace through dialogue. Leo quickly took up their plight by sharing their sorrow publicly and personalizing the tragedy of war.
ALL FOR ONE AND ONE FOR ALL
What is notable about Pope Leo’s criticism of the war is not only the desire to speak out against unjust violence. It is also that he has accomplished something painfully missing under his two immediate predecessors: more unity from the American flock. Left-leaning Catholics saw Benedict (who was pope from 2005 to 2013) as too conservative because he was doctrinaire and comfortable with a smaller, more contemplative church. The reverse was true of Francis, who upset traditional Catholics with his off-the-cuff comments and decisions that created confusion regarding existing doctrine, such as approval of blessings for gay couples. Francis also rejected some beloved traditions, including wearing elaborate vestments, living in the papal apartment, and staying in Castel Gandolfo, the pope’s summer residence, which he opened to the public.
After a pope considered by some to be too conservative and another considered to be too progressive, American bishops and many Catholics, following the Goldilocks principle, see Pope Leo as just right. They view him as combining the social justice instincts and global mission of Francis with the commitment to traditions of Benedict. And as a canon lawyer trained in Rome, Leo is dedicated to doctrinal precision that is likely to endear him to more conservative members of the faith. Archbishop Timothy Broglio, for instance, who oversees clergy serving 1.8 million Catholics in the U.S. military and is widely considered conservative, has been aligned with Leo in his public remarks. In January, Broglio implicitly rebuked the secretary of defense by declaring that Catholic soldiers do not have to follow immoral orders, and then told the television show Face the Nation on Easter Sunday that the war in Iran is likely not justified under Catholic doctrine.
Leo’s actions highlight both sides of his papal personality. Visiting impoverished and war-torn Bamenda, Cameroon, in April, he sang, preached, and cradled babies wearing a gold chasuble decorated with native Toghu embroidery—channeling the humanitarian ethos of Pope Francis. On the same trip, he recited the Pater Noster in the traditional Latin in Douala, Cameroon, and sang the Regina Caeli, also in Latin, in Equatorial Guinea.
Pope Leo is uniquely positioned to challenge U.S. foreign policy excesses.
The substance of what Leo preaches echoes many of Francis’s most sacred causes. But because the current pope’s American accent, training, and deliberate demeanor are so different from that of his predecessor, American Catholics may be more willing to hear Leo—and through this, hear Francis and his message—for perhaps the first time. This will have a profound impact on the church. The American church has been self-referential: it is generous in founding parishes, universities, and hospitals but is mainly focused inward on the health and well-being of Catholicism in the United States. Leo is in a position where he can help merge American Catholics into the world, encouraging them to look and act beyond their own shores.
Many Catholic Trump supporters are taking the pope’s side. They appreciated the president appointing three Catholics to the Supreme Court, which helped end Roe v. Wade in his first term, and applauded his more recent pushback against so-called gender ideology. But Trump’s broken promise to stop endless wars and his insults directed at a man considered Jesus’s representative on earth threatens ongoing Catholic support. An April survey conducted by The Economist and YouGov found that 42 percent of U.S. Catholics supported Pope Leo’s position on the war in Iran, compared with 31 percent for Trump’s. More than six in ten viewed Leo favorably (compared with less than half for Trump or Vance).
As pope, Leo XIV transcends his nationality. But his American identity matters because he is uniquely positioned to challenge U.S. foreign policy excesses. Trump’s attacks have unintentionally helped the pope bridge conservative and liberal Catholics. Catholics are united by Leo’s reminder—in line with his overall vision of a humble, welcoming, and global church—that “no one is called to dominate; all are called to serve.”
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