SEOUL • If the preparations for US President Donald Trump's state dinner in Seoul were any sign, he faces an uphill battle in trying to improve the often fractious ties between South Korea and Japan.

While the menu for the four-course state banquet last night had grilled sole, Mr Trump's favourite fish, it also featured shrimp caught in the waters off Dokdo, the South Korea-controlled islands also claimed by Japan, which calls them Takeshima.

In another jab at Tokyo, a woman forced to work as a sex slave for the Japanese military during World War II was invited to the dinner.

One of Mr Trump's goals on the trip was to boost trilateral cooperation between the United States, Japan and South Korea in the face of threats from North Korean leader Kim Jong Un and China's growing dominance in the Asia-Pacific.

Yet cooperation could once more be hindered by historical grievances stemming from Japan's colonial occupation of the Korean peninsula from 1910 to 1945.

Asked about the shrimp, Japan's top government spokesman told reporters in Tokyo it was important to avoid any actions that would have a negative impact on relations between Japan, South Korea and the US. Mr Yoshihide Suga added that Japan has made its position on "comfort women" clear to South Korea through diplomatic channels.

Historians say anywhere from 50,000 to 200,000 women - many of them Korean - served in Japan's military brothels across Asia before and during the war.

Another dish was beef ribs, accompanied by a gravy made with an "exquisite, 360-year-old soya sauce", said the presidential office.

The age implies it was made in 1657, the year the father of the US Declaration of Independence signatory Benjamin Franklin was born.

AGENCE FRANCE-PRESSE, BLOOMBERG