Last month, U.S. forces used their largest non-nuclear bomb for the first time in combat to strike Islamic State militants in Afghanistan’s Nangarhar province. The weapon, which contained 11 tons of explosives, has colloquially been called the “mother of all bombs.”

The bomb’s nickname did not sit well with Pope Francis, the Catholic leader told an audience of students gathered at the Vatican on Saturday.

“I was ashamed when I heard the name,” Francis said. “A mother gives life and this one gives death, and we call this device a mother. What is going on?”

The April strike was carried out “as part of ongoing efforts to defeat ISIS-K in Afghanistan in 2017,” according to a U.S. Central Command press release.