There were 2 incidents at my office in which Korean men were very friendly to people of other races until they got passed over for promotion. Then all of a sudden, they stopped being friendly to people of other races. They withdrew into their own ethnic crowd.
The first guy turned from a nice friendly guy who publicly disavows racism to someone who is downright mean and abusive to his co-workers, except other Koreans. The only non-Korean he was kind to was a very fair-skinned Japanese woman who was married to a white male. She had two little girls, whom this Korean man would dote on excessively while lying about/to and shouting at his co-workers on the same day. MANY people of other races noticed his new hostility and made an extra effort to be warm and friendly to him, but he rudely rebuffed them.
The second Korean man started out very nice and helpful to people of all races. He claimed all people were always welcome in his company. Then when a white guy was promoted instead of him, he stopped providing support to colleagues' work the way he used to. He was still polite to people outside his ethnic group, but he became distant almost overnight.
When the first guy was being a racist ass, I thought it was an isolated incident. But when the 2nd guy followed his footsteps, though in a more benign fashion, I realized, maybe these guys don't see non-Koreans as real people. We were objects to be used. When they had a chance at the promotion, they used their relationships with us to demonstrate to managers that they were nice people who could relate well to people of other ethnic groups. When the promotions passed to someone else, all reasons for the pretense were gone.
Whether management was right in granting the promotions to the 2 white men over the 2 Korean men is beside the point. Are non-Korean coworkers to be blamed for management's decisions and treated like enemies? In fact, in the 2nd case, many non-Korean coworkers felt the Korean man was more qualified, but the Korean man closed himself off overnight to the same people who were on his side. He did not see they were on his side. He could only see that they were not Korean.
I was very disappointed by what I saw. I originally thought they were friendly because they were interested in people as people, but now I can no longer believe that.