WASHINGTON — A day after the United States and Iran traded prisoners on an airport tarmac in Zurich, Switzerland, US national security adviser Robert C. O’Brien said President Donald Trump would like to hold unconditional talks with Iran, both to secure the release of the other Americans still held by Iran and to address US concerns about Iran’s nuclear program and destabilizing regional behavior.

“The president has offered to talk to the Iranians without preconditions about a whole range of issues,” O’Brien, who previously served as Trump’s hostage envoy, told CBS' Margaret Brennan in an interview today on "Face the Nation."

“We'd like to sit down and talk to them,” O’Brien continued. “But the sanctions and the maximum pressure are not going to be let up until Iran abandons its nuclear program and abandons its malign activities in the region. In the meantime, we'd love to sit down with [the Iranians] and talk about the other detainees. We want to get every single American home.”

Al-Monitor understands that Bill Richardson — a former New Mexico governor and former US ambassador to the United Nations — played a key role in helping advance negotiations for the swap that led to Iran’s release of Princeton scholar Xiyue Wang, who had been detained in Iran since 2016. In exchange, the United States dropped charges against and released a prominent Iranian stem cell scientist, Massoud Soleimani, who was arrested in the United States in 2018 while en route to take up a temporary research position at the Mayo Clinic.