The Southern Sudan Autonomous Region held a referendum on independence in January 2011 as stipulated in the 2005 peace agreement. The result was overwhelmingly in favour, and the state of South Sudan was formally proclaimed on 9 July. However, relations between the former belligerents remained tense, with the Sudan People’s Liberation Movement (SPLM) withdrawing from the Government of National Unity in 2007 (before re-joining the following year) and armed clashes taking place between government security forces and SPLM troops in the contested town of Abyei in 2008 and again in May 2011.1 Furthermore, conflicts continued to rage in other parts of Sudan, highlighting the extreme fragility of the situation. Thus, when fighting erupted between the Government of Sudan and armed groups previously aligned with the SPLM in South Kordofan and Blue Nile at the same time that a major rebellion was launched in South Sudan immediately after independence, there was a great risk of another war (this time, an interstate conflict).2 Understanding the risks involved (and perhaps concerned about the new conflicts both parties were facing), representatives of both states met for talks in Addis Ababa under AU auspices just weeks after South Sudan became independent. The negotiations culminated with an agreement to establish a Safe Demilitarised Border Zone 10km either side of the border and a Joint Border Verification and Monitoring Mechanism (JBVMM), composed of security personnel from both states, to minimise the risk of further conflict.3
Little progress had been made towards establishing the border monitoring mechanisms by the end of 2011, leading the UN Security Council to task the United Nations Interim Security Force for Abyei (UNISFA) with supporting the process.4 The AU and UN continued pressuring the parties to demonstrate their commitment to the border issue. UNISFA began training monitors in December 2012, and the JBVMM conducted its first patrol alongside UN peacekeepers in March 2013.5 For the most part, however, the respective Sudanese and South Sudanese components of the JVBMM were limited to their offices in the capitals of each state and most of the work on the ground was carried out by UNISFA personnel. Even in this limited format, the JVBMM served as a vital ‘hotline’ between the armed forces of each state, helping, for example, to prevent fighting within South Sudan from spilling over into Sudan in 2014.6 Although implementation has not been perfect, the effort to stabilise the border has ended cross-border support for armed opposition groups and helped prevent conflict between Sudan and South Sudan.