The US ambassador to South Korea has some unusual explanations for the harsh criticism he’s faced in his host country.His mustache, maybe? Or a Japanese ancestry that raises unpleasant reminders of Japan’s former colonial domination of Korea? Many South Koreans, however, have a more straight-forward explanation for Harry Harris’ struggle to win hearts and minds in Seoul, and it’s got more to do with an outspoken manner that they see as undiplomatic and rude.

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 mustache 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.

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

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