Obama described North Korea and the actions of its leader Kim Jong Un in regards to developing nuclear weapons pose "a real threat" to the rest of the world, during a speech in Tokyo as part of a four-nation tour of Asia and Oceania.
"Pyongyang has consistently pursued the development of nuclear weapons, Kim Jong Un is not shy about announcing his intentions to produce even more nuclear weapons, test nuclear weapons and develop the delivery system capabilities that pose a significant threat not just to the region but around the world," Obama said.
He also said the North Korean government's isolationism minimizes possible leverage, making negotiations difficult.
"North Korea is an example of a country that is so far out of the international norms and so disconnected with the rest of the world," he said.
Obama added it is important for the United States and Japan to continue to work with other nations such as South Korea and China to advance negotiations with North Korea.
"So far, we haven't seen as much progress obviously as we would have liked. But the one thing that is very important to recognize is that individually, no country can solve this problem as effectively as if we all work together," he said.
During the trip Obama met with Japanese Prime Minister Shinzo Abe for lunch at a sushi restaurant to "renew friendship," according to the Japanese government.
Obama recalled his 2016 visit to Hiroshima as "an extraordinary powerful moment" and hailed Abe's visit to Pearl Harbor as an example of how nations can reconcile following devastating military actions.
"I think the relationship between the United States and Japan is symbolic of the way in which former adversaries can be extraordinary friends and allies and turn swords into plowshares and create prosperity for not only our two countries but also create stability for the world," he said.