Complex sentence: Secretary of State Hillary Rodham Clinton invited Baroness Ashton to undertake joint travel in the Balkans, and the two made unprecedented joint visits to Belgrade and Pristina (as well as Sarajevo) in October 2012.
Split into simpler sentences: Secretary of State Hillary Rodham Clinton invited Baroness Ashton to join travel in the Balkans. They made unprecedented joint visits to Belgeade and Pristina (and Sarajevo) in October 2012.