[IYAS9YAS]

It should be Jong-Un style. Kim is his last name. So Kim Jong would be like saying Smith Jim.

[kempster]

Having been in Korea I can tell you that their last name usually is first as in his grandfather and father:
Kim il Sung
Kim Jong Il
Kim Jong Un

[kempster]

Having been in Korea I can tell you that their last name usually is first as in his grandfather and father:
Kim il Sung
Kim Jong Il
Kim Jong Un