Angela Merkel has arrived in Washington on her first visit as German Chancellor. Three years after their divisive clash over the Iraq war, the new German leader has pledged to improve relations between Berlin and Washington, and work with US President George W. Bush rather than against him.In a message likely to please Bush, Merkel said on Thursday that NATO needed to be more active in fighting terrorism. She also addressed the problem of Iran, whose newly-elected president has repeatedly made anti-Semitic statements over the past months. “When you listen to what they are saying in Iran with regards to Israel and the Holocaust, then we, and the Germans in particular, have to ask ourselves how we should react to these provocative, cynical and insulting statements,” said Merkel. “How far can our beliefs be challenged, how should the West react?” she added. While keen to improve relations, Merkel has also shown she will not shy away from sore subjects. Last week, she openly criticised the US treatment of suspected militants, calling for the prisoner camp in Guantanamo Bay to be closed down. The visit also comes amid controversy over allegations the US secretly used German airspace to transfer terrorism suspects across Europe – accusations which have fuelled anti-US sentiment in Germany.