The internet was always unsecure, even from its beginnings within DARPA, which is why it became ARPA, then ARPANET.
The Russian Oligarchs have no need to understand anything about it except how to control it in wartime, how to prevent social media from causing an antiwar backlash.
The USSR-Afghan war was the USSR’s Vietnam. The uprising caused by it in the country led to the USSR’s downfall. A virulent internet could cause the Russian Federation to split should there be a need to close borders and take a wartime footing.
The US military has no need for the internet for their own comms. They have hardened secure comms and will never rely on the internet or radio. Internet, radio, are used for reaching the public, as for example the Voice of America. The Russian Republic would definitely want to block such comms.
kinda: https://en.wikipedia.org/wiki/DARPA
ARPA was the funding agency. Changed their name to DARPA then changed back. ARPANET was the product.
If you don’t trust wiki, try here
https://www.britannica.com/topic/ARPANET
On the other hand, the unrestricted tolerance of propaganda may be what’s tearing US apart. Moreover, perhaps in this case they want to build a potential information wall to keep US out; with our degeneracy, pornography, propaganda and the rest. I think we probably have ways to accomplish the same, but our intelligence commoooornity would neeeever let us know of the existence of it. Still, I almost wish it would be deployed. The level of filth being regurgitated is beyond tolerance, beyond reason.