Is this their first time?
Invite the white hats or sink. They'll learn.
Japanese defence officials are investigating a reported penetration of the country's high-speed Defence Information Infrastructure (DII) network. The attacks, which Bloomberg attributes to a possible state-based actor, took place in September but have only now come to light. The DII network is shared by the country's Defence …
The need for security being what it is, I think that any Secure Defense network should only be accessible via dialup.
Speeds today are quite reasonable and should be adequate, and having to phone in to a defense server means that you are eminently traceable, virtually eliminating any outsider attempt because of the very real risk of the door being beaten down in minutes and your ass being hauled off for a possibly very long time.
In addition, you could seal off international calls, thus ensuring only people physically in your country could attempt the call, therefor ensuring that your police forces are fully capable of putting down any spurious attempts.
It would indeed have to be one hell of a state actor to attempt anything at that level without insider knowledge.
So why does super-important defense information keep being under threat from any pimply-faced miscreant with an Ethernet port ?