Four of Russia’s nuclear radiation monitoring stations went silent days after a mysterious explosion that led to a radiation spike in northern Russia earlier this month, The Wall Street Journal has reported. Russian officials say at least five nuclear engineers were killed during a rocket test involving “isotope power sources” on a platform in the White Sea, leading to outside speculation that the accident involved a nuclear-powered cruise missile. Four international stations designed to monitor nuclear activity had detected “an event coinciding with the [Aug. 8] explosion in Nyonoksa, Russia,” the world’s main nuclear test-ban body said on Aug. 10.

The Dubna and Kirov stations told the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) they were experiencing “communication and network issues” shortly after the explosion, its chief Lassina Zerbo told The Wall Street Journal. The two stations are part of an international network of more than 300 stations set up to verify compliance with the Comprehensive Nuclear Test Ban Treaty (CTBT). They are the closest Russian stations to the Arkhangelsk region where the blast took place. “We are pending further reports on when the stations or the communication system will be restored to full functionality,” Zerbo was quoted as saying Sunday. Daryl Kimball, the head of the Arms Control Association NGO, called the data disruption “a very odd coincidence.”

To requests on #IMS detection beyond #CTBT, data in, or near the path of potential plume from the explosion are being analyzed . We’re also addressing w/station operators technical problems experienced at two neighboring stations. All data are available to our Member States. https://t.co/pHL4WrHU23 pic.twitter.com/9aO5cQTlls — Lassina Zerbo (@SinaZerbo) August 18, 2019