European researchers have concluded that a radioactive cloud that drifted over Europe in 2017 likely originated in Russia, possibly from a plant that was the site of an infamous nuclear disaster.
Meteorologists and researchers detected the burst of radioactive isotopes in October 2017, and have struggled to determine its origins.
At the time, prevailing winds and other evidence pointed to Russia, but authorities denied responsibility for the release of the ruthenium-106 isotopes. The dispersed isotopes were harmless to human health, but noticeable by monitoring equipment.
This article originally appeared on Radio Free Europe/Radio Liberty. Follow @RFERL on Twitter.