As someone who follows Russian news and political atmosphere. Here’s what’s been happening there as of late: Corona, sanctions and the tremendous drop in oil prices have hit the Russian economy very hard and the situation is projected to get worse. Putin’s rating is the worst it has ever been and the US is currently bipartisan on new, much worse sanctions (rightly so). Putin is becoming desperate. The last time his rating began to drop the invasion of Crimea propped it back up to 90%+ (Russians apparently love invading weak neighbors for territory) and staid that way for a long time despite sanctions and western pressure. Recently, in consistence with the drop in ratings, the saber rattling against Ukraine has picked up a lot. Russia has massed even more troops on the Ukrainian border and preformed a huge mock invasion exercise from Crimea (US reacted by flying stealth bombers in the area). Last week Putin also gave a huge inflammatory interview claiming that Ukraine and other exsoviet countries illegally left the USSR with rightfully Russian territories (a lie). Many see these events as the preparation for another invasion of Ukraine. These nuclear fission byproducts can potentially be the result of Russian weapons tests in preparation for military action that may result in NATO reaction (Ukraine received enhanced NATO status earlier this month, likely in response to the saber rattling). The last time nuclear fission byproducts were detected in the region (last year I believe), it was due to Russia testing a new nuclear engine powered missile with near unlimited range and maneuverability. This missile spews radioactive byproducts as it flies and creates a mini Chernobyl (along with an explosion due to a payload in addition to its reactor engine) where ever it hits. A similar missile was tested in the US but scrapped due to the potential damage to the environment. This of course is just one of many possible explanations for this detection.