From what I understand, a number of them are Chinese nationals. I suspect that taking Chinese slaves might not be a great idea. China tends to carry a big stick; especially in that region.
Wouldn't surprise me, if the DOJ had some "under-the-table" help from Chinese sources, but not in any way that anyone can prove.
If you don't want to sign up for a podcast, John Oliver did a fairly decent bit about it: https://www.youtube.com/watch?v=pLPpl2ISKTg