The article makes a good case that Pearl Harbor was vulnerable to surprise attacks and the Navy had good reasons to be aware of that at the time. However, that

The article makes a good case that Pearl Harbor was vulnerable to surprise attacks and the Navy had good reasons to be aware of that at the time. However, that being the case, what should they have done differently to be less vulnerable? Clearly they needed some kind of early warning system, and they actually installed a radar installation which was brand new technology at the time. (Unfortunately, they didn't heed the warning when it came.) What else should they have done?