Five U.S. citizens imprisoned in Iran have been transferred to house arrest in what is reportedly a first step toward being released. Their freedom would come in exchange for Iranian prisoners in the U.S. and for Tehran gaining access to $6 billion in frozen oil revenue to go toward humanitarian needs. The dual-citizen prisoners were jailed in Iran on unsubstantiated spying charges. The move comes after over two years of negotiations, according to The New York Times. This is Secretary of State Antony Blinken speaking Thursday.

Secretary of State Antony Blinken: “So, this is a positive step, but I don’t want to get ahead of its conclusion, because there’s more work to be done to actually bring them home. My belief is that this is the beginning of the end of their nightmare and the nightmare that their families have experienced.”

Blinken said any exchange will not include sanctions relief for Iran.