Pope Leo says war with Iran is not a 'just war'

Pope Leo XIV talks to journalists aboard the papal flight from Rome to Madrid on June. Alessandra Tarantino/AP hide caption

ABOARD THE PAPAL PLANE (RNS) — Pope Leo XIV said the war in Iran does not qualify as a "just war" according to Catholic teaching.

"I believe it has been already declared clearly," Leo said while answering questions from journalists aboard the papal plane for his six-day visit to Spain.

"There is no just war there," he said, referencing the conflict in Iran.

The question referred to U.S. Vice President JD Vance's remarks in April, where he used just war theory to justify the war in Iran. On that occasion, Vance said the pope should "be careful" when talking about theology.

"When the pope says that God is never on the side of people who wield the sword, there is more than 1,000-year tradition of just war theory," he said. President Donald Trump later said Leo was "weak" on war in a post on Truth Social.

Leo pointed to his most recent encyclical, "Magnifica Humanitas" (Magnificent Humanity), which says that just war theory has "too often been used to justify any kind of war" and is "now outdated."

"The problem is that the just war theory comes from centuries past when we couldn't imagine the weapons, human beings' ability for destruction," Leo said.