Tensions may be running high on the Korean peninsula, but Harry Harris’s facial hair is vying with denuclearisation as the defining theme of his tenure as US ambassador to South Korea.

Harris, a former navy admiral who was born in Japan to a Japanese mother and an American navy officer, has been accused of insulting his hosts by growing a moustache that reminds many South Koreans of the days of Japanese colonial rule.

Japan’s 1910-45 rule over the Korean peninsula is a continuing source of resentment in South Korea, whose relations with its neighbour plummeted last year amid disputes connected to their bitter wartime history.

Social media users in South Korea launched their criticism of Harris’s appearance soon after he was appointed in July 2018, with some noting that during colonial rule all eight Japanese governors-general had sported moustaches.

The 63-year-old Harris told reporters in Seoul last week that he was being singled out because of his background.

“My moustache, for some reason, has become a point of some fascination here,” he said, according to reports. “I have been criticised in the media here, especially in social media, because of my ethnic background, because I am a Japanese-American.”

Harris said he had been largely clean-shaven during his 40-year naval career but had decided to grow a moustache to mark the start of his diplomatic career.

“I wanted to make a break between my life as a military officer and my new life as a diplomat,” he said last month, according to the Korea Times. “I tried to get taller, but I couldn’t grow any taller, and so I tried to get younger, but I couldn’t get younger. But I could grow a moustache, so I did that”.

The newspaper said his moustache “has become associated with the latest US image of being disrespectful and even coercive toward Korea. Harris often has been ridiculed for not being an ambassador, but a governor general”.

Harris has angered some South Koreans with his support for Donald Trump’s demands for the country to pay $5bn towards the cost of hosting 28,500 US troops in the country – more than five times the amount Seoul paid last year.

Last October, 19 students were arrested after they attempted to scale the walls around Harris’s official residence to protest his support for Seoul to shoulder a heavier financial burden.

He has also added to pressure on South Korea to do more to repair ties with Japan, at a time of uncertainty over North Korean denuclearisation talks and a more assertive China.

Harris pointed out that no one had made similar criticisms of moustachioed Korean independence leaders, adding that while he understood the historical background to present-day tensions between Japan and South Korea, he was not going to play down his ethnicity in response to racist comments on social media.

“I am who I am,” he said. “All I can say is that every decision I make is based on the fact that I’m the American ambassador to Korea, not the Japanese American ambassador to Korea.”

And the moustache, it seems, is here to stay. Asked if he intended to shave it off, Harris replied: “You would have to convince me that somehow the moustache is viewed in a way that hurts our relationship”.