This is a "secret"?? As if FReepers couldn't identify most of the same places.
A more important question would be what is the US doing to secure these sites and/or have redundant facilities/suppliers available just in case?
We may know a bit or two about obvious sites, especially inside the country. But very few would know that a certain low-key mine in Zambia provides a certain ore of Unobtainium that the USA has no second source for. In fact, there may be several mines of that kind, which makes the conclusion harder to reach. Just look at rare earths as an example; this became publicly known only when China used it as an economic weapon against Japan. Diplomats and analysts likely knew it all along.
In other words, diplomats and other specialists posted in various countries most likely know more about those countries (and especially about links of those countries to the US interests) than an average US resident, even if the said resident is reasonably educated. There is either too much information for one person to study, or too little information. Many African nations aren't well represented on the Internet and aren't shining democracies. If you want to know the real situation at some facility there you need to talk to a boss there, and he won't talk to you unless you are a US diplomat or a known US businessman or the country's dictator gives him a call ahead of your visit.