I think it is one of policy, and all you have to do is to listen to what the German government has done in asking the U.K. government to apply U.K. law to the U-boats, whose torpedos sank the three Canadian ships that were trying to provide protection, and that are in U.K. territorial waters. The U.K. is quite prepared to do that, and they were very close to doing it until there was intervention on the part of the Government of Canada to prevent it from happening.
On March 19th, 2018. See this statement in context.