A video produced by the White House and presented to North Korean dictator Kim Jong Un Monday was an extremely effective persuasion device, says Dilbert creator and persuasion expert Scott Adams.

The master hypnotist weighed in on the video’s effectiveness Tuesday on Twitter, saying it could very well be “the best thing that anybody ever did in a negotiation.”

Watch Adams’ analysis below:

Also, check out the summit video, posted on the White House Facebook Tuesday: