Pope Leo’s words on Palm Sunday were pointed. “Jesus does not listen to the prayers of those who wage war”, he said during an address at the Vatican.

A few days later in early April, when Timothy Broglio, the archbishop for US military services, was asked on CBS’s Face the Nation if the Iran war is a “just war” in the tradition of the Catholic church, he said: “It is not. While there was a threat with nuclear arms, it’s compensating for a threat before the threat is actually realised.”

US Vice President JD Vance – a recent convert to Catholicism – and Mike Johnson, speaker of the House, pushed back, arguing that the conflict does fit within the church’s just war tradition.

Just war theory, first articulated by St Augustine in the fifth century, outlines the church’s moral guidelines for political and military leaders to consider before choosing to go to war. But it’s not static, and the church’s own position has become more restrictive in recent years.

In this episode of The Conversation Weekly podcast, Jerry Powers, the director of Catholic Peace Building Studies at the University of Notre Dame in Indiana, explains how the Catholic church’s just war tradition evolved and the influence it’s had on US military thinking. Powers was a senior advisor on international policy for the U.S. Conference of Catholic Bishops during the Iraq war, and was involved in efforts to persuade the Bush administration not to invade.

He sets out the difficulty now facing Catholics serving in the US military, whose archbishop has now spoken out against the war they’re being asked to fight. “It puts military officers and especially soldiers in a real conundrum,” says Powers. “A soldier has no choice but to obey orders, and if you disobey orders you could very serious repercussions. The officer question is a different one because officers are more senior, and I think officers have to just resign their commission if at some point, they think this is an immoral war.”

Listen to the interview with Jerry Powers on The Conversation Weekly podcast. This episode of The Conversation Weekly was written and produced by Katie Flood and Mend Mariwany and the executive producer was Gemma Ware. Mixing by Eleanor Brezzi and theme music by Neeta Sarl.

Newsclips in this episode from CB S News, AP Archive, BBC, CBS Sunday Morning, ABC News, Rome Reports, KREM 2 News, MS NOW and WUSA 9.

Listen to The Conversation Weekly via any of the apps listed above, download it directly via our RSS feed or find out how else to listen here. A transcript of this episode is available via the Apple Podcasts or Spotify apps.

Gerard F. Powers received a grant from the Nuclear Threat Initiative that helped support the Catholic Peacebuilding Network's Project on Revitalizing Catholic Engagement on Nuclear Disarmament. He is an expert consultant (unpaid) to the Holy See Mission to the UN. From 1987-2004, Powers was a senior advisor on international policy for the U.S. Conference of Catholic Bishops.