Passage: Flint and de Waal marked the onset of the genocide on 26 February 2003, when a group calling itself the Darfur Liberation Front (DLF) publicly claimed credit for an attack on Golo, the headquarters of Jebel Marra District. Prior to this attack, however, conflict had broken out, as rebels attacked police stations, army outposts and military convoys and the government engaged in a massive air and land assault on the rebel stronghold in the Marrah Mountains. The rebels' first military action was a successful attack on an army garrison on 25 February 2002. The government had been aware of a unified rebel movement since an attack on the Golo police station in June 2002. Flint and de Waal date the beginning of the rebellion to 21 July 2001, when a group of Zaghawa and Fur met in Abu Gamra and swore oaths on the Qur'an to work together to defend against government-sponsored attacks on their villages. Nearly all of Darfur's residents are Muslim, including the Janjaweed, as well as government leaders in Khartoum.On 25 March 2003, the rebels seized the garrison town of Tine along the Chadian border, seizing large quantities of supplies and arms. Despite a threat by President Omar al-Bashir to "unleash" the army, the military had little in reserve. The army was already deployed in both the south, where the Second Sudanese Civil War was drawing to an end, and the east, where rebels sponsored by Eritrea were threatening a newly constructed pipeline from the central oilfields to Port Sudan. The rebel guerilla tactic of hit-and-run raids proved almost impossible for the army, untrained in desert operations, to counter. However, its aerial bombardment of rebel positions on the mountain was devastating.

Question: Which country backed the rebels that threatened the pipeline going to Port Sudan?
Eritrea