Nagasaki Mayor Tomihisa Taue urged world leaders to "bring together as much of your collective wisdom as you possibly can" to permanently eliminate nuclear weapons, and urged them to visit his city to learn first hand the aftermath of a nuclear attack, using President Barack Obama's historic visit in May to Hiroshima as an example. Obama was the first U.S. president to visit Hiroshima, which was attacked three days before Nagasaki.