Was it similar to what we’re seeing now (nationwide, radio related)?
tl;dr: Trains can be stopped by a transmitting a simple, documented tone sequence over analog radio.
Honestly, DB are perfectly capable of clusterf*cking their GSM-R without help from Russia.
I guess by this logic we could also claim that "there Germans caused the power outage in Berlin last winter" because the perpetrators were likely German political activists.
>> It’s believed the perpetrators of the attack were supporters of the Russian war effort, as the stop signals were also joined by broadcasts of the Russian national anthem and a speech from Russian President Vladimir Putin. The attacks have some significance to the invasion of Ukraine, as Poland has been a hub for crucial weapons deliveries supporting the defence of Ukraine.
Yes, yes, it's a code of honour not to use the someone' else national anthem, sure. Especially if you need to bolster the population support for some ongoing cause.