Although I have no doubt that there are SOME women being 'exported' to the United States, I don't think it's a major issue. In China, women are sought after because there's such an imbalance between women and men, and that is certainly not the case here in America. So while there may be a case here or there, I don't think it's any more prevalent than what other countries do.
While there is a possibility of this happening through either human trafficking or even the mail order bride thing, I don't believe there is any real way to know whether or not china is actively importing women to the US unless someone actually comes forward about the issue and the truth is revealed,
Do you mean exporting as in “sending goods and services to another country for sale”? I don’t know, but I would not put it past any nation to sell its women or this nation to buy them. It seems that society on a whole has a problem with respecting women as human beings and not somebody’s merchandise.
A country encouraging people to immigrate is not the same as claiming that country in exporting women. There is an active sex trade in getting women from China to the US, but in that case it isn't that the Chinese government is actively encouraging it, but rather that's what men here seem to want.