Pope Leo says US-Israeli war against Iran does not qualify as a ‘just war’

Pope Leo XIV has said that the war being waged by the United States and Israel against Iran cannot be considered a “just war” under Catholic teaching, arguing that the centuries-old doctrine is no longer applicable in an era of advanced military technology and weapons capable of mass destruction.

Speaking to journalists aboard the papal plane during his six-day visit to Spain on Saturday, the pontiff was asked whether the conflict in Iran could be justified through the framework of the “just war” theory, a concept previously invoked by US Vice President JD Vance in defence of Washington’s military actions against Tehran.

'No just war'

“I believe it has been already declared clearly,” Leo said. “There is no just war there,” he said, referencing the conflict in Iran.

The pope further elaborated on his position by arguing that the traditional doctrine emerged in a vastly different historical context. “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.

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Leo also addressed the situation in Lebanon, noting that he remains in contact with religious leaders in the country. “The situation is very complex,” he said, as Israeli military operations continue in southern Lebanon.

Trump calls Pope 'weak'

President Donald Trump later criticised the pontiff, describing him as “weak” on matters of war in a post on Truth Social. Leo, however, rejected the criticism and maintained that he would continue speaking out against armed conflict.

About ongoing war between Russia-Ukraine

During the same flight, the pope also expressed concern about the ongoing war in Ukraine. “I am worried for Ukraine,” Leo said. “We must really push to reach an end to the conflict and the war and find a solution.” Calling for continued negotiations, he added, “Already, four years and a half have passed. We must reach a solution.”

The latest remarks underscore Pope Leo XIV’s consistent opposition to war and his call for diplomacy as the primary means of resolving international conflicts.