"Knowing what we know about civilian casualties, a just war cannot be fought today," said Jeffery Nicholas, an associate professor of philosophy at Providence College in Rhode Island.
He made the comments in an interview with Catholic News Service on the continuing Russian invasion of Ukraine in light of just-war principles.
"What kind of munitions Russia is using — which are not 'smart' munitions," Nicholas said. "just obviates any application of just-war theory, especially on the part of the aggressor."
CNN, as well as other news outlets, are reporting that Russia is relying more heavily on "so-called 'dumb' bombs than on its arsenal of precision-guided munitions" in its war on Ukraine, adding, "These indiscriminate weapons kill scores of civilians."
"On the part of the defendant," Ukraine, Nicholas added, "the resistance is targeting specifically the combatants coming into Ukraine so they're generally adhering to just-war" principles.
One argument Russia is using to justify the invasion is to protect the Russian population in the southeastern Ukrainian regions of Donetsk and Luhansk, known collectively as Donbas and controlled by Moscow-backed separatists.
"Justification for secession is a difficult topic," said Gerard F. Powers, director of Catholic peacebuilding studies for the Kroc Institute for International Peace Studies in the Keough School of Global Affairs at the University of Notre Dame. He also is coordinator of the Catholic Peacebuilding Network.