A Wall Street Journal opinion piece has ignited a debate over Pope Leo XIV’s application of just war doctrine to modern conflicts, particularly the U.S.-Israel war on Iran.
A Wall Street Journal opinion piece has ignited a debate over Pope Leo XIV’s application of just war doctrine to modern conflicts, particularly the U.S.-Israel war on Iran.

A series of letters to the editor published in the Wall Street Journal on May 6 questioned Pope Leo XIV’s repeated calls for peace, arguing that his stance lacks clarity on justifiable national defense and fails to recognize that some wars are necessary.
"I have already spoken from the very first moment of being elected... I said, ‘Peace be with you,’ and the Church’s mission is to preach the Gospel, to preach peace," Pope Leo said May 5, directly refuting a false claim by President Donald Trump that he supports Iran obtaining nuclear weapons. "The Church has spoken for years against all nuclear weapons, so there is no doubt there."
The debate centers on the Catholic Church’s long-standing “just war” doctrine. For a war to be justified, all criteria must be met: it must fight a grave evil, cause less damage than the evil it eliminates, have a serious prospect of success, and be a last resort after all diplomatic options are exhausted. Pope Leo has argued the war in Iran fails on multiple counts, citing that diplomacy has not been exhausted and the disproportionate harm to civilians is morally unacceptable.
This theological disagreement has sharpened a diplomatic rift between the Holy See and the Trump administration ahead of Secretary of State Marco Rubio’s scheduled visit to the Vatican this week. The meeting follows public criticism from President Trump, who called the pontiff “weak on crime and terrible for foreign policy” in April after the pope’s appeals for peace in the U.S.-Israel war on Iran.
The pope’s firm anti-war position is not a recent development but a continuation of a ministry forged during years of turmoil in Peru. According to Armando Jesús Lovera Vásquez, who knew the future pope in Peru, he consistently “advocated for democracy and the defense of human rights” during the country’s internal war against the Shining Path guerrilla group in the 1990s. Later, as a bishop in Chiclayo, he mediated disputes between peasants and mining companies.
“He is not speaking as a politician,” said Father Jorge Millán Cotrina, rector of Chiclayo’s cathedral. “He is speaking from the Gospel.” This perspective, rooted in decades of pastoral work in the Global South, informs his critique of international conflicts, focusing on human dignity and the devastating impact of violence on the poor and marginalized. His approach mirrors that of his predecessors, including Pope John Paul II and Pope Benedict XVI, who spoke out against the Gulf War and World War I, respectively.
The tension between the two world leaders escalated after President Trump repeatedly and falsely claimed the pope endorsed Iran’s nuclear ambitions. “I donʼt want a Pope who thinks itʼs OK for Iran to have a Nuclear Weapon,” Trump wrote on social media April 12. Pope Leo has consistently condemned nuclear arms, stating in a March 5 video message, "May the nuclear threat never again dictate the future of humanity."
Secretary Rubio downplayed the rift, telling reporters that Trump’s criticism was rooted in his opposition to Iran ever obtaining a nuclear weapon. U.S. Ambassador to the Holy See Brian Burch said the secretary’s visit would proceed in a spirit of “fraternity and authentic dialogue” to discuss Middle East policy and work through any differences. The meeting comes as a fragile ceasefire between the U.S. and Iran, which began April 8, continues to hold.
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