During the Cold War, Germany's partition by the Iron Curtain made it a symbol of East–West tensions and a political battleground in Europe. However, Willy Brandt's "Ostpolitik" was a key factor in the "détente" of the 1970s. In 1999, Chancellor Gerhard Schröder's government defined a new basis for German foreign policy by taking a full part in the decisions surrounding the NATO war against Yugoslavia and by sending German troops into combat for the first time since World War II.