Visiting U.N. Secretary-General Ban Ki-moon called Monday on the leaders of Japan, China and South Korea to engage in a dialogue “in a forward-looking manner” and lay the foundation for peace and reconciliation in the region.

Speaking at the outset of a symposium at United Nations University in Tokyo, Ban said Northeast Asia holds the key to promoting cooperation in the 21st century, which is often referred to as “the era of Asia and the Pacific.”

“The United Nations have been engaging in a number of regional cooperative mechanisms, but Northeast Asia still remains a missing link,” Ban told the audience. “I sincerely hope that the dialogue between countries in the region, in particular, Japan, China and the Republic of Korea, will proceed in a forward-looking manner.”

Ban urged the leaders of the three countries to “be future-oriented, remembering the past,” for genuine reconciliation, harmony, peace and prosperity.

“This will generate a spirit of peace and reconciliation for generations to come. We should move forward in a spirit of cooperation for mutual benefits to achieve common prosperity,” he stressed.

Relations between Japan and China as well as Japan and South Korea have been strained over territorial and historical disputes.

Prime Minister Shinzo Abe had a much-anticipated summit with Chinese President Xi Jinping in Beijing in November, but Abe and South Korean President Park Geun-hye have not held a formal one-on-one meeting since taking office, Abe in 2012 and Park in 2013.

The South-Korean born Ban, in Japan to attend the U.N. World Conference on Disaster Risk Reduction in Sendai, expressed gratitude for Japan’s numerous contributions to the international community, commending the country as “a proactive contributor to humanitarian operations, development activities, peacekeeping, human rights and human security.”

“The United Nations deeply appreciates and values our partnership with Japan. We are tomodachi, we are friends,” Ban said. “I look forward to strengthening our cooperation even more.”

Meanwhile, Abe said in a speech following Ban that the international community needs to be “united” more than ever in the face of transnational issues such as terrorism, climate change and infectious diseases.

“Our country is determined to lead discussions on all issues in any stages within and without the United Nations,” Abe said, pledging further support for sustainable development, promotion of women’s social status and health issues.

Abe also told the audience that Japan is ready to serve as a new permanent member of the U.N. Security Council, calling for “concrete results” in reform of the council.

Japan is seeking a permanent seat along with Germany, Brazil and India as the so-called Group of Four.