One of the sticking points between north and south Sudan has been the presence of Darfuri rebels in the south. Khartoum has repeatedly accused Juba of training the Justice and Equality Movement (Jem), the main rebel group in Darfur. Juba has always denied the allegations. Sudanese foreign minister Ali Karti warned last month that southern support for Darfur rebel groups could lead to war with the new country.
Cross-border security issues are a major preoccupation in the north, according to Said Mohamed al Khatib, a northern negotiator of the 2005 Comprehensive Peace Agreement.