Spies that are foreign citizens acting to help their own country are not usually considered traitors. Even if they assume a fake identity. So a Russian citizen

Spies that are foreign citizens acting to help their own country are not usually considered traitors. Even if they assume a fake identity. So a Russian citizen spying US on the account of Russia would be a spy, but not a traitor. These spies are indeed usually captured (if discovered) and eventually exchanged. A traitor would be for instance a US citizen spying on the US to help China, or Russia. Or a Chinese citizen spying on China to help the US. This is a much more perilous situation than just being a spy...