Rashid Abdi – one of the most shrewd commentators on the Horn of Africa has posted these Tweets – which have been slightly revised to make them easily to read. The background is not by Rashid, and has been added.

“Sudan says it is asserting sovereignty over the al-Fashaga triangle. And it is right. Region is internationally recognised as Sudanese. Ethiopian PM Meles Zenawi who was more astute sought modus vivendi with Sudan rather than challenge its sovereignty. This allowed Ethiopian farmers to lease land, not own land.

“A large-scale and prolonged war between Sudan and Ethiopia will be catastrophic. It almost certainly will draw in Egypt. That will be a nightmare scenario. Makes sense for PM Abiy to negotiate with Sudan rather than use military means to challenge Khartoum’s seizure of al Fashaga.

“PM Abiy is sadly in a bind and terrible fix. His only support base now is hardline Amhara imperio-nationalists. They drove him to war with Tigray, now pushing him to another even bigger war with Sudan. When he fails to deliver, they will depose him.

“Eritrea’s President Isaias Afewerki always wanted supremacy, dominance in the Horn. The turmoil in the Horn is his chance. Tigray was existential & immediate threat. A weak & conflicted Ethiopia suits him fine. An Ethiopia at war with Sudan even better. That way he gets to kill two birds with one stone.”

How this conflict escalated

The  dispute over the al Fashaga triangle  goes back to treaties signed by Britain, Italy and Ethiopia in 1900, 1901 and 1902. The triangle is very fertile and well watered land, which has been cultivated by Amhara farmers from neighbouring Ethiopia. But the land is generally regarded as Sudanese.

The background to this complex problem can be read here.

As  NIZAR MANEK, MOHAMED KHEIR OMER argued in an article in Foreign Policy:

“Fashqa is an approximately 100-square-mile territory of prime agricultural land along its border with Ethiopia’s Amhara state, which Sudan claims by virtue of an agreement signed in 1902 between the United Kingdom and Ethiopia under Emperor Menelik II and subsequently reinforced by various Ethiopian leaders, including the TPLF.  The dispute over Fashqa remains a major grievance for Ethiopia’s ethnic Amhara farmers near the border, who seek to till the land, and is an obstacle in negotiations over the Grand Ethiopian Renaissance Dam (GERD).”

Former Sudanese President Omar al-Bashir largely turned a blind eye to incursions into his country by Ethiopia. However, Sudan’s transitional government, which took power after popular protests that ousted  al-Bashir, took steps to get the Ethiopian farmers to leave al-Fashaga.

When the war in Tigray erupted on 4 November, the Ethiopians withdrew their army from the al Fashaga – to join the fighting in Tigray. The Sudanese seized their opportunity – and took large parts of the disputed area.

Failed attempting to resolve the conflict

On Sunday 13 December Sudan’s Prime Minister Abdalla Hamdok visited Ethiopia with an offer to broker a ceasefire in its northern Tigray region, a proposal Ethiopia said was unnecessary because fighting had stopped.

As the AFP report put it: “Hamdok, who was accompanied by Sudanese security officials, planned to present his concerns about threats to Sudan’s security along its border with Tigray during the visit, the officials said. However, Hamdok returned within a few hours from what Ethiopian Prime Minister Abiy Ahmed had earlier described as a two-day trip.”

PM Hamdok – who had hoped to resolve the al-Fashaga problem during the visit, had been snubbed by Ethiopia’s PM Abiy. He returned to Khartoum bruised by the encounter. No useful discussions were held to end the Ethiopia-Sudanese crisis during the regional summit in Djibouti of IGAD. Rather, the crisis escalated.

Reuters reported on 16 December the Sudanese armed forces as saying that a number of its officers had been ambushed by “Ethiopian forces and militias” during a security patrol of the border region. “During the return of our forces from combing the area around Jabal Abutiour inside our territory, they were ambushed by Ethiopian forces and militias inside Sudanese territory, as a result of which lives and equipment were lost,” the army said, adding the attack took place on Tuesday. The Sudanese army did not specify how many officers were killed. Local residents said that reinforcements were being sent to the area, which is part of the Fashaqa locality where some Ethiopian refugees have been crossing into Sudan.

Sudan responded by reinforcing its troops in the disputed areas.  Egypt – Sudan’s traditional ally – said it would back Khartoum. Egypt’s Foreign Ministry condemned the Ethiopian cross-border attack on Sudanese military troops near Sudan’s border with Ethiopia. The ministry termed the attack as an “unjustified assault.” “Egypt reiterates its full solidarity with brotherly Sudan and affirms its support to the country’s right to protect its security and sovereignty over its territory,” the ministry said in a statement. The statement continued, “Egypt is following these dangerous field developments with great concern … and underlines the need to take all possible measures to guarantee that such incidents against Sudan will not be repeated in the future.”

On 29 December Ethiopia warned Sudan that it would mount a counter-offensive to take re-assert its control of the al-Fashaga triangle. “If Sudan does not stop expanding into Ethiopian territories, Ethiopia will be forced to launch a counter-offensive,” Ethio FM 107.8 quoting Foreign Ministry spokesman Ambassador Dina Mufti as saying.

Now that conflict appears to have erupted into full scale fighting.

Consequences of a Sudan-Ethiopia conflict

It is too early to be certain how this will develop. Much depends on how far Sudan and Ethiopia will push this conflict. The reactions of Egypt and Eritrea will also be important – while regional actors like the African Union could be important.

As Rashid Abdi said in the Tweet quoted at the start of this article, “A large-scale and prolonged war between Sudan and Ethiopia will be catastrophic. It almost certainly will draw in Egypt…Eritrea’s President Isaias Afewerki always wanted supremacy, dominance in the Horn. The turmoil in the Horn is his chance. Tigray was existential & immediate threat. A weak & conflicted Ethiopia suits him fine. An Ethiopia at war with Sudan even better. That way he gets to kill two birds with one stone.”

The conclusions by Nizmar Makek and Mohamed Omar in Foreign Policy is also useful.

If Khartoum does so, it has much to lose. Abiy could retaliate by supporting Sudanese rebel groups following unstable peace accords they signed with Sudan’s transitional government in October—for example, in Sudan’s Blue Nile state, which borders Ethiopia’s Benishangul-Gumuz state, the site of the GERD. Isaias could also support subgroups of the Beja—a group of tribes living between the Red Sea and the Nile—in a tactical alliance with him against the Beni Amer ethnic group in eastern Sudan and Eritrea traditionally aligned with the ELF, as well as seek to enlist discontented Sudanese opposition figures who were previously based in Eritrea from the mid-1990s to 2006. Since the fall of Bashir, tensions have erupted in eastern Sudan—including in Kassala, Gadaref, and Port Sudan—between groups aligned with Eritrea’s government and those opposed to it.

Meanwhile, Eritrea is getting involved; it is hosting the ENDF on its territory although it remains unclear if Eritrea’s own forces are involved in fighting. On Tigray state television, Tigray’s regional president Debretsion Gebremichael said forces aligned with Isaias bombed Humera—a strategic Tigrayan town on the triple frontier between Ethiopia, Eritrea, and Sudan on Nov. 9 with heavy artillery, that Eritrean and Tigrayan forces are fighting on the border, and that ENDF forces have otherwise been restricted in their movements. While Abiy’s government earlier claimed it had captured territory from Humera to Shire, about 160 miles east in Tigray, it quickly retracted that claim.

Despite initial successes, the TPLF may not have the backing of Sudan to keep going, especially if Abiy and Isaias can make compromises to enlist Sudan’s support. Although everyone from Sudan’s Hamdok and the African Union to Pope Francis and the U.S. Senate Foreign Relations Committee is calling for a cease-fire and negotiations, Abiy will only call for talks if the ENDF and other security forces continue to fragment to a point of no return and fail on the battlefield. Without Sudan, a cornered TPLF—which is no stranger to ruthless and violent tactics—might attempt to overthrow Abiy’s government or seek to assassinate him with the support of his many other enemies.