Catholic theologians urge Trump to follow just war doctrine as Iran conflict continues

The U.S. and Israel launched joint military strikes on the Islamic Republic of Iran last weekend, prompting the regime to retaliate with drone and missile attacks on Israel, American bases and assets, Gulf state airports and energy infrastructure, and other targets.

As both sides continue to exchange firepower, Catholic theologians who spoke with EWTN News are cautioning President Donald Trump to maintain moral clarity in his decisions and conduct by complying with the long-standing Catholic tradition of just war doctrine.

“[Following just war doctrine is] not just important, but imperative,” said Joseph Capizzi, dean and ordinary professor of moral theology and ethics at The Catholic University of America.

“Governments must consider these principles of just war because they are first and better understood as principles of good governance, or statecraft,” he said.

For a war to be justified, according to the Catechism of the Catholic Church, it must be waged to fight against a grave evil, the damage caused by waging the war cannot be graver than the evil it is meant to eliminate, there must be a serious prospect of success, and all alternatives to war must have already been tried.

Taylor Patrick O’Neill, theology professor at Thomas Aquinas College, told EWTN News that every condition must be present for a war to be just. He said a war is sinful “if you fail to meet a single one of those criteria.”

Just cause and last resort

Trump’s justification is based on claims that the regime is seeking a nuclear weapon through its uranium enrichment program.

Last year in June, Trump ordered the bombing of Iran’s Fordow Uranium Enrichment Plant and asserted at the time that Iran was “a few weeks away from having a nuclear weapon.” Officials gave conflicting reports about the success of the strike and how far back it set Iran’s nuclear program, ranging from months to years.

Trump’s claims appeared to conflict with testimony three months earlier from Tulsi Gabbard, director of national intelligence, who said the intelligence community assessment is that “Iran is not building a nuclear weapon” and that Supreme Leader Ali Khamenei had not even authorized a nuclear weapons program.

Trump revived discussions with Iran in January 2026 with the same allegations and demanded Iran enter a deal in which it would end or reduce uranium enrichment and scale back its ballistic missiles program.

In a Feb. 27 interview with CBS’ “Face the Nation,” Omani Foreign Minister Badr Al Busaidi — a mediator for the negotiations — said Iran agreed to many concessions. The country agreed to reduce uranium enrichment and reduce its stockpile to a level at which Iran could “never, ever have [the] nuclear material that will create a bomb” and it would submit to inspections.

Al Busaidi said he believed “the peace deal is within our reach,” but less than a day later, Trump launched Operation Epic Fury, which began the military attacks on Iran. Trump said on March 3: “It was my opinion that they were going to attack first.”

O’Neill told EWTN News that for a war to be justified, it needs just cause and a right intention, meaning that a war is not justified by a just cause if “really your intention for going into war is something else.”

He said Catholics have a right to “question whether or not just cause is present” and “question whether or not right intention is present.” He said there would need to be an “imminent” threat, such as if there is “some weapon or [if] some type of military action is currently being planned and will be executed.”

O’Neill said it’s often difficult for the general public to know whether the cause is legitimate or whether it truly is the last resort: “We don’t know what options have been tried previously.” He said there could be information unavailable to the public that’s “part of the moral calculus.”

Capizzi said that when considering whether military action truly was the last resort, it should be “measured in terms of the gravity of the threat” and the impact of failing “to decrease or end that threat.”

He said a more severe gravity of a threat could accelerate the timeline toward “a just use of force.”

Proportionate force and an end goal

Trump addressed the nation on March 2 to thank the U.S. military for killing Iranian military leadership and to promise an escalation in strikes.

He said the mission could last four to five weeks but did not say who would control the country when the mission is complete. Previously, he said he may work with new leadership within the regime but also urged Iranians to revolt and take control over the country.

To determine whether the damage caused by the war will be graver than the evil it is meant to alleviate, Capizzi said the goal must be “peace … measured by justice and order and tied to actual, achievable political outcomes.” He said “merely to decapitate the head of a regime is not a sufficient political outcome, as it creates political disorder that is very difficult to control.”

O’Neill said there “should have to be some kind of plan and a real expectation that this plan is going to be successful” to make the determination. He said the criteria for just war cannot be met if “it’s not very clear what the goal is.”

“There would have to be some sort of plan and that plan would have to be based off of intelligence [assessments] and very credible information as far as what happens to Iran after these strikes,” he said.

O’Neill said the moral calculation would also have to consider the results of prior interventions in the Middle East, such as Afghanistan, Iraq, Syria, and Libya.

He said if previous plans “failed to be brought to fruition … then of course you’d have to look at that in any regime changes going forward” when trying to meet the just war criteria of success being likely and for Iran’s situation being better when the mission is complete.

Iran’s death toll is at least 1,230, according to Iran’s Foundation of Martyrs and Veterans Affairs and reported by state-run media. The deaths include Khamenei and dozens of military and government officials as well as civilians. More than 160 civilians were killed by a strike that hit a girls’ elementary school in Minab, according to Iranian Foreign Minister Seyed Abbas Araghchi.

Israeli strikes on Lebanon, launched in response to Hezbollah attacks, killed 72 people based on numbers from the Lebanese Ministry of Health, according to the Lebanese Broadcasting Corporation International. Six members of the U.S. military have been killed, according to U.S. Central Command. At least 12 people have been killed in Israel, according to the Israeli-based Ynet News. Another 11 people were killed in other Arab states, according to the Qatar-based Al Jazeera.

These death totals are as of the morning of March 5.