U.S. President Donald Trump speaks during a news conference in the James S. Brady Press Briefing Room at the White House in Washington April 6, 2026. Trump lashed out at Pope Leo XIV on social media and in a verbal interview April 12, calling him "weak on crime" and "terrible for foreign policy," as tensions escalate in the Mideast. (OSV News photo/Evan Vucci, Reuters) Irish moral theologian Dr Vincent Twomey SVD has said that President Trump’s threat to bomb Iran back to the Stone Ages breached the understanding of lawful self-defence.
Responding to a question from this paper — that the Church’s understanding of Just War may be seen as a bit old fashioned, i.e. sometimes pre-emptive military action is needed when diplomacy is exhausted — Dr Twomey said that ‘Old-fashioned’ is not a moral concept, except in the sense that, thanks to modern means of mass destruction, her moral principles may sound ‘old-fashioned’. One of the strict conditions to engage in a war of lawful self-defence is that ‘the use of arms must not produce evils and disorders graver than the evil to be eliminated.’ [CCC 2309]. What could be graver than Trump’s threat to destroy the 5000-year-old Iranian civilisation back to the stone ages?”
He added that the idea of just behaviour in war has been often abandoned. “The political philosopher Eric Voegelin noted that WW1 was the first war ever waged with the intent not to defeat but to liquidate the enemy. It was not to be the last. WW2 was marked by the abolition of the moral principle that forbids the direct killing of civilians or the destruction of their means of livelihood. The Russia war against Ukraine has constantly offended in this regard. The obliteration of Gaza is a more dramatic example — and now the obliteration of Lebanon. Trump threatened to destroy the Iranian desalination plants and so the supply of fresh water needed by the 90 million civilians.”
Dr Twomey said the age we live in no longer recognises objective moral principles. “The Church’s moral principles — which are in fact universal moral principles expressed by international law — seem old-fashioned because we live in an age that no longer recognises the compelling force of objective moral principles. As Ratzinger once put it: we live under the dictatorship of relativism. According to Desmond Fennell, the American bombing of civilians in Hiroshima and Nagasaki marked the end of Western civilisation — because it endorsed the denial of the fundamental moral principle that the end can never justify the means, sacrificing the innocent to put an end to the war.”
He added: “Trump is on record for his contempt of international law. He embodies the most basic immoral principle: might is right.”
Finally, Dr Twomey pointed to the Catechism’s insistence that moral legitimacy of war rests on “the prudential judgement of those who have the responsibility for the common good.” He asked: “Can anyone who behaves so irrationally, whose reasons for going to war change day by day, who imagines himself as Our Lord, make a prudential judgement?”