Russia is decrypting 256-bit radio. Cryptographers HN is it plausible?

made a new post that's better titled... can't delete this one. https://news.ycombinator.com/item?id=36003391

/ Seems like they've both caught on.. Here is the original post. Not sure if there's a way to merge.

I'm part of a subreddit that reads defence reports and tries to keep up with "credible" news about the War in Ukraine. A newly released report by RUSI (The Royal United Services Institute, the world’s oldest defence and security think tank) says that Russians are now "near real time" decrypting 256-bit Motorola radio communications by Ukrainian forces. Here is the relevant passage. Ukrainian officers recalled one incident in which the Russian headquarters gave pre-emptive warning to its units of an artillery strike based on Ukrainian troops calling in a fire mission. The Ukrainian troops were communicating with Motorola radios with 256-bit encryption, but it appeared that the Russians were able to capture and decrypt these transmissions in near real time. The most likely system for such functions is the Torn-MDM. (57)

They cite two interviews with Ukrainian military personnel and their own analysis of the system as a source:

57. Technical assessment of Torn-MDM conducted in Ukraine, June 2022

Some are saying this is impossible, that near real time decryption of 256-bit encryption is not possible.

I'm not an expert, so I'm punting over to the cryptographers here at HN. Could this be? Is it possible/feasible to do battlefield decryption of 256-bit radio encryption?

I don't know the particular model of the Motorola radio they are referring to.

Here is the report in question. Page 23 https://static.rusi.org/403-SR-Russian-Tactics-web-final.pdf