This has Russia written all over it. They've been participating unconventional "warfare" for many years now.
Think of cyber/social media activities against the West, propaganda, invading Crimea without admitting to having troops in the area, covert assassinations of adversaries in the West, and psychological operations against Western diplomats in Russia.
NATO restricts their regular military options, so they exert influence in any way they can. I believe the only reason we haven't been told Russia is number one suspect is Trump administration's warm ties to that direction.
Think of cyber/social media activities against the West, propaganda, invading Crimea without admitting to having troops in the area, covert assassinations of adversaries in the West, and psychological operations against Western diplomats in Russia.
NATO restricts their regular military options, so they exert influence in any way they can. I believe the only reason we haven't been told Russia is number one suspect is Trump administration's warm ties to that direction.