Pope Francis on Saturday criticized the naming of the U.S. military"s biggest non-nuclear explosive as "the Mother of All Bombs," saying the word "mother" should not be used in reference to a deadly weapon.

"I was ashamed when I heard the name," Pope Francis told an audience of students on Saturday. "A mother gives life and this one gives death, and we call this device a mother. What is happening?"

Pope Francis is set to meet U.S. President Donald Trump on May 24 in a potentially awkward encounter given their opposing positions on immigration, refugees and climate change.