U.S. Ambassador to Japan Rahm Emanuel on Tuesday expressed confidence that the trilateral partnership between the United States, Japan and South Korea will be "sustainable" due to "shared interests" between all three countries.

Conversely, China, North Korea and Russia cannot forge a similar relationship as "they don't share strategic interests in the same collaborative, cooperative way that we do," Emanuel told Kyodo News and other media in Tokyo.

The ambassador also played down concerns that the outcome of the U.S. presidential race in November next year and elections in the two key U.S. allies in Asia would affect the trilateral cooperation, saying "shared interests are pretty powerful."

U.S. Ambassador to Japan Rahm Emanuel speaks to the press in Tokyo on Dec. 5, 2023. (Kyodo) ==Kyodo

The U.S. presidential election could become a re-match of Democrat Joe Biden and former President Donald Trump, a Republican who pursued his "America First" unilateralist policies and pressured allies in Asia to pay for more of the costs associated with hosting U.S. troops in their countries.

South Korea is scheduled to hold a general election in April. Japan could also have a general election as early as next year if Prime Minister Fumio Kishida decides to call one.

While the trilateral relationship has been overshadowed by historical issues between Japan and South Korea, Emmanuel praised the progress made so far by the two Asian neighbors through direct dialogue.

"My experience is that it's better that Japan and Korea talk to each other than through the United States," he said while revealing that the pair had asked Washington not to get involved.

Emanuel urged the continued use of "dialogue and diplomacy to make the most of (the) future" given the "complicated" history surrounding all three countries.

Signaling the growing trilateral collaboration, the three countries held the first standalone trilateral summit at the U.S. presidential retreat of Camp David in August, with Biden, Kishida and South Korean President Yoon Suk Yeol agreeing to expand cooperation in security and other issues amid North Korea's nuclear and missile threats and China's assertiveness.

Relations between Tokyo and Seoul have improved under the conservative administration led by Yoon, who took office in May 2022, with the South Korean government proposing a solution to a thorny dispute over wartime labor compensation in March this year.