The Russians have targeted CIA officials who have been involved in Russian operations, as part of their hybrid warfare strategy, causing dissension and removing quality intelligence officers from the intelligence game. It is very obvious they're targeting specific individuals, including senior intelligence service officers.
According to investigations by the US intelligence community, there has been a correlation between the travel of Russian intelligence officers and locations where US officers were attacked. The exposure to sarin gas, believed to cause the Gulf War Syndrome, was from US military strikes on Iraqi sarin stockpiles which made thousands of US military personnel sick.