WARSAW — Polish police have arrested two suspects on charges of disrupting railway traffic by transmitting a radio signal that tricks trains into emergency stops.
The men, ages 24 and 29, are from Białystok, a city of 300,000 in northeastern Poland close to the Belarusian border. Polish media reported that they had long been interested in amateur radio.
The authorities confirmed Sunday that the suspects had broadcast an emergency signal — known as a “radio stop” — on frequencies used by train operators in three Polish regions.
The most serious disruption was the first attack around midnight on Friday, which halted about 20 trains in northwestern Poland. Following the stop signal, the perpetrators aired Russia’s national anthem and an excerpt from a speech by Russian President Vladimir Putin, Polish media reported.
Regional cargo traffic was suspended until 2 a.m., Polish railway infrastructure operator PKP PLK said.
Poland’s ABW counterintelligence agency launched an investigation and initially hinted at foreign interference.
“[The incident] must be explained due to the current state of threats to the Polish state,” Stanisław Żaryn, the deputy chief of Polish special services, said in a video on Saturday.
Poland is a key conduit for weapons heading to Ukraine.
The Law and Justice party government said the incidents were tied to the campaign ahead of Poland’s October 15 general election — a very close contest in which the ruling party is aiming to win a third straight term in office.
“The parliamentary elections are coming up, we have a war situation. It is about a kind of destabilization,” Deputy Interior Minister Paweł Szefernaker told private broadcaster RMF FM on Monday.
While the motives of the accused are still unknown, the incidents highlighted a long-standing security problem with railway communication systems. Poland still uses open radio frequencies for such signals; it plans to upgrade to encrypted systems by 2025.
Technical specifications of the emergency stop signal and how to build a sequence triggering automatic stops are public, are not encrypted and do not require authentication, the IT security website Niebezpiecznik.pl said.
It’s not the first such incident. Trains were halted in 2010, and in 2011 three drunk men hid in bushes near a rail line in Kraków to stop trains by radio, Niebezpiecznik reported.
Following the detention of the two men Białystok, another unauthorized transmission of the emergency stop signals was reported in Wrocław.