In December 2009, she became the inaugural High Representative of the Union for Foreign Affairs and Security Policy that was created by the Treaty of Lisbon. As High Representative, Ashton served as the EU's foreign policy chief. Despite being criticised by some, particularly at the time of her appointment and in the early stages of her term of office, for her limited previous experience of international diplomacy, Ashton subsequently won praise for her work as a negotiator in difficult international situations, in particular for her role in bringing Serbia and Kosovo to an agreement in April 2013 that normalised their ties, and in the P5+1 talks with Iran which led to the November 2013 Geneva interim agreement on the Iranian nuclear programme.