Hi Paul,
Thanks for your comments.
There are no plans, plus theres no need to reintroduce
captive Siberian tigers back to the wild.
However theres a project by WWF to reintroduce captive
bred Persian leopards back to the wild.
Without captive breeding this project would not be possible.
For more information about this reintroduction project see this link-
WWF - Reintroducing endangered leopards to the Northern Caucasus
regards,
Craig