An offensive codenamed Operation Mistral 2 against the VRS in western and northern Bosnia followed in September. Croat forces pressed towards Banja Luka, the capital of Republika Srpska. Some US representatives, including Galbraith, Clark, and Holbrooke, advised Šušak to take as much territory from Republika Srpska as they could, but with the exception of Banja Luka. In October, the HV-HVO force came within 16 miles south of Banja Luka. The Serb leadership was forced to start peace negotiations or risk the capture of its capital. The negotiations produced the Dayton Agreement, where Šušak was one of the key Croatian negotiators in Dayton. He also worked on an agreement regarding the peaceful reintegration of eastern Slavonia to Croatia.