USA has the death penalty for treason too. Now you can argue back and forth (US wants China to eventually be democratic so I'm helping China by spying for CIA...etc) but they essentially betrayed their country. Chinese efficiency: Torture them till they tell want they know and then teach others a lesson along the way too.
Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States.
https://www.law.cornell.edu/uscode/text/18/2381
Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States.