Former German Foreign Minister Hans-Dietrich Genscher died on Thursday night at the age of 89.

The cause of death was a cardiovascular disease, according to his office’s statement.

Mr. Genscher was a member of the German libertarian Free Democratic Party and held the office of Foreign Minister for about two decades. He was the longest-serving foreign minister in Germany’s history.

He played an important role during the crucial years of German reunification by keeping West Germany’s embassies open to East Germans and other refugees coming from behind the Iron Curtain.