The US ambassador to South Korea has some unusual explanations for the harsh criticism he has faced in his host country, suggesting his moustache or Japanese ancestry could be factors.

Many South Koreans, however, have a more straightforward explanation for Harry Harris’ struggle to win hearts and minds in Seoul, and it has got more to do with an outspoken manner that they see as undiplomatic and rude.

Since arriving in Seoul in July 2018, Mr Harris, a retired navy general born to a Japanese mother and an American navy officer, has been the focus of keen attention because of his military and ethnic background.

The 63-year-old former US Pacific Command chief has sometimes drawn criticism from those who take issue with his manner when dealing with South Koreans.

His moustache has become the subject of ribbing online, with jokes made about how it resembles those of Japanese colonial masters, who brutally occupied the Korean Peninsula from 1910-45.

But there is more serious concern that the discord could widen a growing rift in Seoul’s relations with Washington at a time when diplomacy with rival North Korea seem in danger of imploding.

Mr Harris recently said his appearance and ethnicity have been a source of his criticism in South Korea.

“My moustache, for some reason, has become a point of some fascination here,” Mr Harris told a group of foreign reporters in Seoul last week.

“I have been criticised in the media here, especially in social media, because of my ethnic background, because I am a Japanese-American.”

It is not the first time a US ambassador in South Korea has been in the news for things other than diplomacy.

In 2015, former ambassador Mark Lippert was slashed in the face and arm by an anti-American activist.

But unlike Mr Lippert, Mr Harris has repeatedly irked many South Koreans since President Donald Trump sent him to Seoul.

South Korea US Envoy Mustache
A protester plucks a moustache from a picture of US ambassador to South Korea Harry Harris (Lee Yong-hwan/AP)

After meeting Mr Harris in November, Lee Hye-hoon, then chairwoman of the South Korean parliament’s intelligence committee, said that the ambassador repeated about 20 times Mr Trump’s calls for Seoul to drastically increase its financial contribution to US troop deployment in the South.

In recent months, four students were arrested after they broke into Mr Harris’ Seoul residence during an anti-US rally.

A mock moustache was plucked from his picture at another demonstration.

Mr Harris said his moustache has nothing to do with his Japanese background and that he started growing it only to mark the start of his career as a diplomat.

“To those people, I say that you are cherry-picking history,” Mr Harris said, adding that some Korean independence fighters also had a moustache.

Mr Harris said he understands the historical animosity that exists between Japan and South Korea.

“But I’m not the Japanese-American ambassador to Korea,” he said.

“I’m the American ambassador to Korea.”