'US envoy Kennedy urges Japan, S. Korea to mend ties'
US Ambassador to Japan Caroline Kennedy (R) shakes hands with Japanese Foreign Minister Fumio Kishida at Kishida's office in Tokyo on January 24, 2014 - by Yoshikazu Tsuno
Ties between the two American allies have regularly been strained by a long-standing territorial dispute over a group of tiny islands, and issues arising from Japan's colonial rule over the Korean peninsula early last century.
On Saturday, South Korean President Park Geun-Hye warned Japan that it would face "isolation" if it pushed ahead with a move to revisit an apology over wartime sex slavery.
"I think that the two countries really should and will take a lead in this process, and the United States, being a close ally of both of them, is happy to help in any way that we can," Kennedy said in an interview aired by Japanese broadcaster NHK, according to Kyodo News.
Kennedy, calling Japan and South Korea "the two closest United States allies in the region", said "good relations are in everyone's interest".
Kennedy, the only surviving child of assassinated US president John F. Kennedy, also said Japanese Prime Minister Shinzo Abe's December visit to the controversial Yasukuni Shrine in Tokyo was unfortunate.
"Anything that distracts from all the positive work that we do together and makes the regional climate more difficult is something that is not as constructive moving forward," the envoy said, according to Kyodo.
Yasukuni is a memorial to about 2.5 million war dead, but is controversial because those commemorated include a number of senior figures condemned to death at the end of World War II for their role in directing the conflict.
Earlier this week, Danny Russel, the assistant US secretary of state for East Asia, called on Japan and South Korea to look at the model of Japan and the United States, which have overcome the bitterness of World War II to nurture a close friendship.
Echoing remarks from Secretary of State John Kerry on a visit last month to Seoul, Russel said Japan and South Korea shared common challenges including uncertainties over nuclear-armed North Korea.