Obama made the remark during a joint press conference in Japan after holding a summit meeting with his Japanese counterpart. The two leaders talked for little over an hour.
"Given the threat from North Korea, we agreed to continue reinforcing deterrence and strengthening our defense capabilities," Obama said.
Later this week, Obama will make a historic visit to the Japanese city of Hiroshima. He earlier said it is to demonstrate his commitment to a nuclear-free world.
"Our visit to Hiroshima will honor all of those who were lost in World War II and reaffirm our shared vision of a world without nuclear weapons, as well as highlight the extraordinary alliance that we have been able to forge over these many decades," Obama said. (Yonhap)