I suspect that they were using classical ML techniques, and a lot of traditional scientific computing techniques, but not a lot of deep learning, given how new it is, and how slow government operates.

It's also not clear how a lot of the classical ML can be translated into a DL setting- a lot of graph analysis [1] is traditionally solved using matrix factorisation, for instance, which doesn't directly translate into deep learning. You can find different ways of doing it with DL, but it's not as transferable.

[1]: e.g. analysing an individual's social graph. I believe that Facebook uses a lot of classical techniques, like PCA. I've heard that Facebook has been pouring a lot of money into research that uses DL on arbitrary graphs.