How did a 38-second video improve diplomatic relations with countries that don’t share a formal alliance with each other?

In September 2016, as an act of “public diplomacy” the United States military released a 38-second video meant to address the growing tensions in the Korean Peninsula and emphasize military cooperation between the U.S., Japan, and South Korea. At the time of its release, North Korea had just performed its fifth nuclear weapons test, while relations between Japan and South Korea were deteriorating. Just a few months after its release and with more than 100,000 views, the Washington Post reports that effort of the U.S. military might actually work. A study conducted in Japan found that after viewing the video, support for strengthening military cooperation between Japan and South Korea improved.