Similarities Between Korean and Vietnamese
The image below comes from a tragic story, Vietnam's Unexploded War Legacy, but I post it only to make a simple linguistic observation:

The Vietnamese word for "danger" is remarkably similar to the Korean word for the same: 위험 (ui heom). Both come from the Chinese 危險 (Mandarin: wēixiǎn). Interestingly, the Vietnamese and the Korean pronunciations are closer to each other than either are to the Mandarin. This is something I've noticed many times in my acquaintance with the three Asian languages, which all come from different language families. I have a hunch that Sino-Vietnamese and Sino-Korean are phonetically closer to Cantonese, Hokkien, Hakka or another "dialect" than they are to Mandarin, but having only studied the latter, I could not say.