Japanese citizens angry at South Korea's role in a diplomatic row over their wartime history that has spilled into trade have found some unlikely allies: South Korean commentators using YouTube to attack their own president, Moon Jae-in.

The South Korean leader has drawn the ire of conservative commentators at home for wrecking ties with Japan, a former colonial ruler that is now a key economic partner and fellow security ally of the United States.

To thousands of Japanese viewers, the YouTube channels offer a rare honest appraisal of Moon, whose detractors see as an untrustworthy man who has turned against a neighboring democracy while courting the dictator of North Korea.