Not all international disagreements are disagreements between sovereign nations themselves. It's possible that MAEU could sue JAXA or Hokkaido University in a J

Not all international disagreements are disagreements between sovereign nations themselves. It's possible that MAEU could sue JAXA or Hokkaido University in a Japanese court if they think they're violating Japanese law. If that's not the case, or if the Diet passes a new law that protects their countrymen in this dispute, then yeah it becomes the type of conflict you describe.