Diplomatic activity like this, yes, in the past has tended to indicate impending attacks. If it steps up, particularly if some neutral nations in Iran who have embassy or consular services in Teheran start emptying them out, or sending non-essentials and family members home with no explanation, you will know something is up. I watch what the Japan Foreign Ministry does, but if it indicated something was immenent to me, I could keep it to myself and would certainly not post it here in open forum where Iranian intelligence or their friends could lurk. The element of surprise is going to be very important, not that they would not be monitoring the foreign embassies themselves though. This latest twist with UK-Iran, and the explosions, makes it get very interesting. Especially for the month of December.
Not sure anything is going to be a *surprise* but, I understand the need for such.