BERLIN (AP) — Mike Pompeo is making his first visit to Germany as secretary of state at the start of a four-nation European trip as tensions rise between the U.S. and Iran.

Pompeo was set to meet Foreign Minister Heiko Maas and Chancellor Angela Merkel in Berlin on Friday before continuing to Switzerland, which has long represented Washington's interests in Tehran and has in the past been an intermediary between the two.

Germany is one of the signatories to the 2015 nuclear deal between Iran and world powers that is trying to keep it alive after the U.S. withdrew last year.

Pompeo's stop in Berlin makes up for a visit that he abruptly called off in early May to fly to Iraq. He is also traveling to the Netherlands and Britain.