In a statement on Wednesday the U.S. State Department Spokesperson Morgan Ortagus said Secretary of State Mike Pompeo has in a phone thanked Swiss Foreign Minister Ignazio Cassis as the U.S. protecting power in Iran and assistance in repatriating imprisoned U.S. citizens from Iran.

"Secretary Pompeo thanked Foreign Minister Cassis for Switzerland’s continued and constructive role as our protecting power in Iran and for its assistance in caring for and repatriating U.S. citizens wrongly imprisoned by the Iranian regime," the statement said.

Pompeo himself described the call "terrific" in a tweet and said he had discussed "deepening economic ties and partnership to develop a COVID-19 vaccine and treatment" with his Swiss counterpart. The Swiss Foreign Minister is scheduled to make a three-day official visit to Tehran on September 5 to mark the centenary of Swiss-Iranian diplomatic relations. Switzerland currently holds “protecting power” mandates to mediate between Iran and the US, Canada and Saudi Arabia.

According to a statement released by the Federal Council of Switzerland, Ignazio who is also a federal councillor will meet with President Hassan Rouhani, Foreign Minister Mohammad-Javad Zarif, and Secretary of the Supreme National Security Council Ali Shamkhani. Discussions will focus on bilateral relations and Switzerland's protecting power mandates, the statement said.

Switzerland has represented U.S. interest in Iran since January 1980 after diplomatic relations between Iran and the United States came to an end with the U.S. embassy takeover and hostage-taking. Since 2017 Switzerland has also assumed protecting power mandates for Iran in Saudi Arabia and for Saudi Arabia in Iran and in 2019 it also came represent Iranian interests in Canada.