DUBAI/WASHINGTON (Reuters) – The United States and Iran each freed a prisoner on Saturday in a rare act of cooperation between two longtime foes whose ties have worsened since President Donald Trump took office.

Iran released Xiyue Wang, a U.S. citizen who had been held for three years on spying charges, while the United States freed Iranian Massoud Soleimani. He had been facing charges of violating U.S. sanctions against Tehran.

A senior U.S. official said Washington was hopeful that Wang’s release would lead to the freeing of other Americans held in Iran and that it was a sign Tehran was willing to discuss other issues.

Wang appeared to be in good health and humor, he said.

Switzerland facilitated the swap. Iranian Foreign Minister Mohammad Javad Zarif met Soleimani in Zurich, state news agency IRNA said and it later reported Soleimani’s arrival in Iran.