The Heglig Crisis was a brief war fought between the countries of Sudan and South Sudan in 2012 over oil-rich regions between South Sudan's Unity and Sudan's South Kordofan states. South Sudan invaded and briefly occupied the small border town of Heglig before being pushed back by the Sudanese army. Small-scale clashes continued until an agreement on borders and natural resources was signed on 26 September, resolving most aspects of the conflict.

Prior to independence from Sudan two civil wars were fought in the region from 1955 to 1972 and from 1983 to 2005, in which 2.5 million people were killed and more than 5 million externally displaced. South Sudan peacefully gained independence from Sudan on 9 July 2011 with Sudan's long-term president Omar al-Bashir promising to "work with our southern brothers and help them set up their state". Despite this relations between the two states have been marked by conflict over the disputed oil-rich Abyei region. In January 2012, South Sudan shut down all of its oil fields over a disagreement with oil transit fees imposed by Sudan.

International arbitration committees such as the Abyei Boundaries Commission 2005 and the Permanent Court of Arbitration 2009 did not definitively resolve the question of administrative control over Heglig, as the dispute remained linked to whether the area lay east or west of the 1931 administrative line.

In May 2011, it was reported that Sudan had seized control of Abyei, with a force of approximately 5,000 soldiers after three days of clashes with South Sudanese forces. The precipitating factor was an ambush by South Sudanese forces on May 19 which killed 22 northern soldiers. The northern advance included shelling, aerial bombardment and numerous tanks. Following the advance South Sudan withdrew its forces from Abyei and declared the movement of Sudanese forces into Abyei to be an "act of war". The United Nations sent an envoy to Khartoum to intervene. A deal on militarization was reached on 20 June 2011. The United Nations Interim Security Force for Abyei, consisting of Ethiopian troops were deployed under a UNSC resolution from 27 June 2011. In early December 2011, Jau, a town in Unity state in South Sudan, was occupied by Sudanese forces. In early March 2012, the Sudanese Air Force bombed parts of Pariang county.

Both countries accused each other of supporting rebels on their soil as part of the ongoing internal conflicts in Sudan and South Sudan.

The national parliament in 1980 and the government in Khartoum in 2004 made administrative and map changes to annex the oil fields to Western Kordofan.

On 26 March, the Republic of Sudan claimed that South Sudan attacked the Heglig oilfield, located in the Sudanese state of South Kordofan, while South Sudan claimed that their forces had carried out an operation within the borders of South Sudan. The South Sudanese attack was supported by the Sudanese rebel group JEM, which attacked from South Sudanese state of Unity. The following day, the Sudanese Air Force launched a bombing raid on the Unity oilfield in Unity, located to the north of the state capital, Bentiu. The Sudanese Army later attacked the disputed areas of Jau, Pan Akuach, and Teshwin, but were repelled by the South Sudanese Sudan People's Liberation Army (SPLA).

South Sudanese artillery positions 20 kilometres north of Bentiu, which had been involved in the shelling of Heglig, were bombarded by artillery from the northern side of the border. Sudan's Information Minister, Abdallah Ali Masar, confirmed that South Sudanese had penetrated 10 km into Sudanese territory, but also claimed that Sudanese forces had repelled them and driven them back, and had taken several prisoners.