A man in Tokyo walks past a screen showing a TV news report on a North Korean missile test on March 6. (Koji Sasahara/AP)

There is rising tension on the Korean Peninsula. North Korea appears increasingly aggressive, conducing multiple missile tests. Meanwhile, relations between Japan and South Korea are quite poor. After South Korean activists placed a statue of “comfort women” in front of the Japanese Consulate General in Busan, South Korea, in December, the Japanese government recalled its ambassador to Seoul in protest.

The U.S. military has sought to address this tension via “public diplomacy.” For example, in September, after North Korea had conducted its fifth nuclear weapons test, the U.S. Pacific Command published a 38-second video.

The video seeks to emphasize U.S.-Japan-South Korea military cooperation to counter the growing threat from North Korea, even though Japan and South Korea do not have a formal alliance. The video shows U.S. B-1B bombers taking off from Andersen Air Force Base on Guam, being escorted first by Japanese F-2 fighters over Japanese territory and then by South Korean F-15 fighters over South Korean territory.

The video also includes such statements: “US Air Force Strategic Bombers Trained with Fighter Aircraft from Japan and Republic of Korea,” “‘These Flights Demonstrate the Solidarity between South Korea, The United States, and Japan to Defend Against North Korea’s Provocative and Destabilizing Actions …’ — Admiral Harry B. Harris Jr., Commander of US Pacific Command,” and “Cooperation with Japan and the ROK Broaden capabilities to Defend Against Threats.”

The video has since been viewed more than 100,000 times. But should we expect it to make any difference? Could it actually improve strained relations between Japan and South Korea?

One test is to see whether it changed minds in Japan — where, for example, 70 percent support Japan’s withdrawing its ambassador from South Korea. In January, we conducted an online experiment that involved 1,050 people from Yahoo Cloud Japan. We randomly assigned half of these people to watch the video about Japan and South Korea. The other half watched an unrelated video about a U.S.-Australia military exercise.

Here’s what we found:

  • People who watched the video were more supportive of Japan-South Korea military cooperation. About 45 percent of those who watched the video supported further strengthening cooperation between Japan and South Korea, compared with 38 percent of those who watched the other video. There were similar increases in support for cooperation in other realms, such as the economy, environmental protection and disaster prevention — even though none of these are mentioned in the video. In other words, watching a 38-second video only once was enough to change Japanese views on cooperation with South Korea.
  • At the same time, people who watched the Japan-South Korea video became a bit less supportive of sharing military information with South Korea and deploying the Japanese military alongside the United States to help South Korea. It may be that the video led some Japanese to fear involvement in a crisis on the Korean Peninsula.

Of course, this experiment is necessarily artificial in that it asked people to watch the video. Most people aren’t surfing the U.S. Pacific Command website of their own accord. Nevertheless, watching the video even once did have an effect, increasing Japanese support for cooperation with South Korea even though relations between the two countries were at historically low levels.

For the United States, the question going forward is whether such diplomatic efforts could help strengthen an alliance with Japan and South Korea against an increasingly threatening North Korea.

Yuki Asaba is a professor at the University of Niigata Prefecture. Tetsuro Kobayashi is an associate professor at the City University of Hong Kong and Kobe University. Atsushi Tago is a professor in international relations at Kobe University.