Given the record of political interference in the delivery of the Bushehr power plant, it is no wonder that Iran refuses to swap their Uranium outside of Iran's borders. It is easy to predict that in 2025, the US would STILL be dragging their feet on delivering the enriched Uranium back to Iran. I certainly can't blame Iran for refusing a trade anywhere except inside Iran, given this track record.
U.S. says working on initiative to de-escalate Syria fighting, with focus on Aleppo (Reuters)
from the article: Clinton urges Russia to delay launch of Iran nuclear plant