How did the United States contribute to the initial division of the Korean Peninsula along the 38th parellel?

American troops led the offensive beyond the 38th parallel, pushing the North Koreans toward the Yalu River, which separated Korea from Communist China

what is the other part to the question

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.