Containing Dangerous Ideas?

What could the Pentagon be doing to thwart the spread of dangerous ideas- that is, ideas considered dangerous by the powers that be? Certainly such are already filtered via the mainstream' media entities by their hiring, firing, fraternal-ism, ect. But how can such be done on the wide open internet?

Filter- to reduce the potential audience. We already are aware of the concept of internet filtering, if only of a fraction of the ways it may be used to ensure that fewer people see the dangerous idea.

Jam- to reduce the potential audience by jamming the internet with false-front sites: those purported to be by some concerned anonymous citizen but are actually Pentagon or other ancient regime entity product. These are marked by the same dynamics seen in "mainstream" media in limiting the scope of topics deemed "acceptable" by selective inclusion/exclusion.