The Biden administration agreed Monday to unfreeze approximately $6 billion in Iranian assets in exchange for the release of five American citizens held for years by the theocratic Tehran government.

The hostages had been moved to house arrest last month from Iran’s notorious Evin prison, in what the White House hailed as a tentative first step as negotiations were finalized.

Human rights attorney Jared Genser had identified three of the five hostages as Siamak Namazi, businessman Emad Shargi, and environmentalist Morad Tahbaz.