During his speech at Hiroshima, Barack Obama used his remarks to push for a nuclear-free world and to reflect upon the deaths of the Japanese, Koreans and American POWs who perished in the first use of an atom bomb. On Friday, Obama became the first sitting U.S. president to visit the site, an act that looked dangerously close to an apology for a difficult decision that saved lives and hurried the end of World War II. For what it’s worth, the White House insisted Obama was not apologizing to Japan. His sentiments were heartfelt but will be soon forgotten, for the world surrounding Hiroshima has long disregarded the lessons in the skeletonized buildings and blackened trees.

“The world was forever changed here,” Obama said, “but today the children of this city will go through their day in peace. What a precious thing that is. It is worth protecting, and then extending to every child. That is a future we can choose, a future in which Hiroshima and Nagasaki are known not as the dawn of atomic warfare but as the start of our own moral awakening.”

But as The Wall Street Journal opined, Obama should have used the backdrop of Hiroshima to warn the world of a new asymmetric nuclear threat. Jihadists dream of setting off a bomb in a U.S. urban center. A president grounded in reality would admit that signing pieces of paper, making international promises and lifting sanctions on countries like Iran in no way ensures nuclear nonproliferation. Heritage Foundation’s 2016 Index of U.S. Military Strength labels North Korea as the most severe threat to U.S. vital interests because it threatens to use its nuclear weapons. Currently, China is poised to deploy nuclear-powered submarines armed with ballistic missiles tipped with nuclear warheads while America’s military continues to deteriorate. A true leader would see the future threat and take steps to prevent violence on a nuclear magnitude. It’s a moral responsibility.