I think it helps to start by thinking like an adversary, right? Whether you're a government or an organization that is thinking about threats overall, you need to go through: What is an adversary? How are they going to try to hold me at risk? What are they going to try to do to me? What am I willing to lose? Once you have a sense of what your core interests are, what you're willing to lose and what you need to protect, then you can start building a strategy for investment. That doesn't quite get you there to answer your question, however.
In the United States, we passed an executive order about cybersecurity that called out something called the section 9 list. The Department of Homeland Security conducted an assessment of all the companies and organizations in the country that were most cyber-vulnerable, and the impact of which, if disrupted, would cause the most significant damage. That analysis led to a list, which is classified. It's not a very large number of companies; you could probably guess a number of them right off the bat. That also helped the government focus on its collaboration with those key companies. That way, you can say that we're going to ensure the cyber-defences of these companies are going to be hardened.
That does not mean that those are the only companies the country would focus on. The military, for example, has to look at the adversaries, Russia, Iran and North Korea in particular, and ask: What are they investing in? What are they going to go after? What are they going to try to do? You have to try to blunt and block them if they do something quite significant.
That also doesn't quite get us there, and this is where regulation has to come in. If you've hardened the most valuable companies in a country, if the military is watching the most valuable adversaries, it's the Internet. It's massive. Someone is going to try to hack somewhere else and they're always going to look for the weakest underbelly—wherever they can go.
A great example here is Iran in 2012. The United States was prepared for Iran to do all sorts of things during the nuclear negotiations. What Iran did, which we were able to prognosticate that they would do, was to go after the infrastructure in the Persian Gulf of Saudi Aramco. They hacked Saudi Aramco, as has been publicly reported. That's where regulation absolutely has to come in and say that there have to be breach management requirements; there have to be penalties if companies don't meet these breach management requirements, and companies have to be able to meet certain resiliency investments to defend against breach.