Maybe they were paid for it. Maybe they were threatened or blackmailed for it. Maybe they feel a political, religious, or ethnic loyalty to another country. Plenty of people in the US are more than happy to do things that run counter to the US' interests. The entire American military-industrial complex directly benefits from the US being more in danger because it means they get more money.
If a Russian colonel aboard a submarine refused direct order to launch a nuke at the height of the cold war, I think we can assume very few are the people ready to deal with nuclear bombs for a buck.
Many things can cross moral boundaries, but I think I d rather deal in drugs and slaves, tanks and assault rifles than uranium, if only for money. And if not for money, only for national survival.
We struggled in France to finish our fusion bomb design and a british double agent pointed us at the best model we had that was similar to the british one, we're not sure if he did it for France or because the British wanted us to have it too, but it wasn't for money, for instance, even if it was a terrible decision to make as a human for him Im sure.
To transform them into the bad guys instantly? No thanks, I'd rather give them enough troops and conventional weapons so that whatever thing Russia throws at them is being intercepted, and Russian land troops essentially would hit a wall.
That way Russia would be forced to either withdraw (= Putin political and possibly physical death), continue until all their conventional arsenal is depleted (= same as above, just later), or resort to nukes (= likely destruction by NATO).
