While looking at the State Department's website, I came upon a story where issues of North Korean sex trafficking were presented at the Woodrow Wilson Center yesterday. Citing the imense poverty in North Korea as the catalyst of the problem and the lack of transparency from China on the data and details concerning how they actually process trafficked persons is leading to a dire humanitarian situation. Tha article mentions that China recently took steps in December of 2007 to outline the China National Plan of Action on Combatting Trafficking of Women and Children. Time will tell if China will be a helpful partner in this awful situation of human trafficking of North Koreans.
The issues of how and why North Korean women are trafficked over the Chinese border are explained in this 1996 article entitled Brides, Bruises and the Border: The Trafficking of North Korean Women into China.