The use of diplomatic passports turns this into a different beast for European tradition as well. It further inflames the crime of the conspiracy and raises it to certainty in their eyes. There may even be treaty language that equates this as if it were successful and if so, could trigger some pretty interesting mobilizations.
In clarification, we may already be in the second phase of World War IV and not know it yet. If so, I believe our old friends in France are getting in it with both feet. Thank God.