Yamamoto championed the view that civilian diplomacy and person-to-person exchanges conducted by nongovernmental organizations had a critical role to play in international relations.
Yamamoto also helped to found the Shimoda Conference in 1967, a private sector forum for the discussion of bilateral issues between American and Japanese policymakers and policy experts.
[1][7] He became interested in the social changes occurring in the U.S. at the time, including the civil rights movement, and the election of President John F. Kennedy,[1] whose table he waited on during the 1960 campaign.
[3] During his keynote speech at the 1967 Shimoda Conference, Mansfield made a public call for the establishment of a privately sponsored exchange between members of the US Congress and the Japanese Diet so they could build mutual understanding and speak frankly and off-the-record about common challenges.
These exchanges are credited by early participants, such as Speaker of the US House of Representatives Tom Foley, U.S. Secretary of Defense Donald Rumsfeld, and Senate Majority Leader Howard Baker, for introducing a generation of American leaders to Japan and creating the personal ties that later were important in defusing trade tensions and strengthening bilateral cooperation in a range of areas.
He promoted improved relations with Europe, South Korea, China, and Southeast Asia through the nongovernmental exchanges and Track 2 policy dialogues.
[14] As informal advisor to Prime Minister Keizo Obuchi and other leaders, his influence paved the way for Japan’s adoption of the approach as a main tenet of the country’s foreign policy.
While promoting policy dialogues and political leadership exchanges, Yamamoto also championed efforts to develop Japan's nonprofit sector and to encourage the growth of philanthropy in Asia.
[16] During his later years, Yamamoto worked to strengthen Japan's contributions to global health and the fight against HIV/AIDS and other major communicable diseases in Africa and other parts of the developing world.
[17] By bringing Japanese politicians to Africa to speak with people battling AIDS and arranging for overseas celebrities such as Bono to raise awareness of the need for Japan to do more to help poor countries, the initiative played a key role in encouraging the Japanese government to triple its annual contribution to the Global Fund from 2005 to 2012, making it one of the world’s most generous supporters of the battle against the global AIDS epidemic.
[5] Columbia University professor Gerald Curtis, who knew Yamamoto for more than forty years, noted that he never abandoned his beliefs that exchanges between democracies should be spearheaded by the private sector.
[1] The former director of the editorial board at Asahi Shimbun, Yukio Matsuyama, also stated that, "Yamamoto did more for international exchange than anyone else did, both in name and reality, having had nothing to start with ...