Here is a totally different slant on things.
I met a couple on DC that were from England and had been just about every where in the world. Some how we got on the subject of the Panda and both had visited a Panda Preserve in China.
They both felt that there was something a bit fishie about the place as all the secure trails had been shut down to visitors. They never saw one living Panda.
Their feelings were that China has so miss handled the preserve that most likely there were very few left.
Putting 2 and 2 together I would guess if this couple are correct and the Chinese found out about the losses due to say negligence, there would be riots, suicides and firings squads.
It is possible that the Chinese are recalling breeding pairs on loan to other country's in hopes of boosting a very frail population of Pandas before the country's realises how badly they screwed up.
Naturally this may not be the only game in town, but it was 3 years ago when I met these people and as I look back on the pictures we took of these amazing beasts, so mild looking but darn right vicious as adults, I can understand why China wants them back.
It is sad as their home in DC is heaven on earth for them. Their enclosure is state of the art, there is nothing they lack. To return these Pandas to China and a life of having to fight each other for food or mates, little shelter from the weather and no one minding their health. this will cause stress, they won't be around much longer either.
Just another side of the coin to think about.