Pope Leo XIV and U.S. bishops have said the war fails just‑war criteria, warning it lacks proportionality, last resort, and a clear moral end.
Former U.S. Attorney General Bill Barr made the case for Americaʼs war with Iran as meeting Catholic criteria for a just war.
Barr, a Catholic, said because Iranʼs potential use of nuclear weapons posed a legitimate threat to the U.S., Europe, and the Middle East, the war doesnʼt violate just war doctrine. President Donald Trump claims U.S. force prevented Tehran from rebuilding its nuclear program after he repeatedly said Iran’s nuclear sites were “completely and totally obliterated” following earlier U.S. strikes.
Barr said the Iran war doesnʼt clearly violate just war doctrine during an April 23 panel discussion hosted by the NAPA Institute.
“The traditional position of the Church was to exhort leaders to take into account all the factors, but not to say, ‘thatʼs wrong’ unless it clearly violated the just war doctrine, which this obviously doesn’t,” Barr said.
However, just war criteria require a present and certain attack, and speculative or future threats fail the “lasting, grave, and certain” standard. Every condition must be met for a war to be just.
‘If we allow this window to go by’
Barr, currently a senior fellow at the Catholic Information Center, said the U.S. faced “difficult questions dealing with nuclear weapons” and argued that allowing the window of opportunity to dismantle Iranʼs nuclear capabilities to pass by would result in grave consequences.
“If somethingʼs obviously out of bounds, you can say the Nazis, you know, should not have invaded this, or, you know, Saddam Hussein should not have invaded Kuwait. But thatʼs not the situation we face,” he said.
“We face these very difficult questions dealing with nuclear weapons,” Barr said. “We’ve tried for a long time to deal with it, and if we allow this window to go by, the costs in the future are much higher, and the likelihood will be that the people won’t be willing to pay that, and nuclear weapons will be deployed by Iran.”
“Youʼre basically weighing these imponderables and risks,” he said. “If the cost of dealing with it later and allowing them more time to reach a certain level of conventional force will make it almost impossible to deal with it without massive losses, including in Europe, certainly in the Middle East and certainly among Americans, then those future costs have to be taken into account and say thereʼs a window now.”
“When youʼre faced with some of these difficult issues, itʼs very easy to stand back and say, turn the other cheek, or take an absolutist position [that] ‘you shouldnʼt be violent,’” Barr said. “But that begs the question, that doesnʼt really solve the problem, and deal with the real issue at stake that other people have to deal with.”
Barr also said he believed “the primary temptation of religious people is self-righteousness,” which he said Pope Francis “was very good to call attention to.” He said he has seen Catholics on both ends of the political spectrum fall into “virtue signaling,” which he said, “is not coming to grips with the real moral choices and the real practical reality.”
Reflecting on his upbringing, Barr said his father got him interested in St. Augustine, the fourth- to fifth-century theologian who developed criteria morally limiting when war may be justified.
Barr further credited his parents with helping him remain strong in his faith.
“My parents always said, ‘Think things through, donʼt just take your belief like itʼs a suit off a rack in a store and say, ”OK, Iʼm putting this coat on, this is what I believe.“ Understand why you believe it,’” he said.
Barr’s remarks come as Leo calls for peace and Church officials question the justification of the war on the basis of just war doctrine. Vatican Secretary of State Cardinal Pietro Parolin and Archdiocese of Washington, D.C., Cardinal Robert McElroy have said they do not believe the war fits just war criteria.
Leo has said the Iran war fails to align with just war theory, citing failure to exhaust all diplomatic resources, disproportionate civilian harm, and lack of clear moral objectives. The U.S. bishops have publicly backed Leo, stating that just war teachings do not morally authorize unchecked military violence.
Popes seldom issue blanket rulings but Pope Benedict XV made clear World War I lacked moral legitimacy given its scale, civilian toll, and lack of proportionate ends. Pope John Paul II warned the Gulf War did not meet just war criteria. And the Vatican also formally stated in 2003 the Iraq invasion failed just‑war standards, especially preventive war doctrine.
Pope Leo XIV urges peace
The Holy Father has said “God does not bless any conflict” and said that “anyone who is a disciple of Christ, the Prince of Peace, is never on the side of those who once wielded the sword and today drop bombs.”
On Palm Sunday, Leo stated that Jesus “does not listen to the prayers of those who age war, but rejects them, saying: ‘Even though you make many prayers, I will not listen: Your hands are full of blood.’”
Leo has garnered sharp criticism from the Trump administration after speaking out multiple times against using God to justify military action in public speeches, homilies, and social media posts.