Ethiopia and Eritrea - former foes now united against local militias in Tigray

Ethiopia's federal government is inching closer to victory in Tigray, where violence between the government and regional militia has triggered a refugee crisis in the region, and has caused a media blackout. Ethiopian Prime Minister Abiy Ahmed is receiving help from neighbour - a longtime foe who recently joined in to help.

Ethiopia's war within has now escalated into a regional conflict, and neighbouring countries are taking sides. Eritrea, a former foe, is assisting prime minister Ahmed by sending soldiers to battle the local militia in Tigray.

Diplomats stationed in the region stand by this account. But officially, both sides have denied Eritrean involvement. Until recently - Ethiopia and Eritrea were sworn enemies. In 2018, they signed a peace deal putting a two-decade conflict to rest.

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Abiy Ahmed was the architect of this peace, for which he also received a Nobel Peace Prize. Now, the two governments are closer than ever and liberated against The Tigray People's Liberation Front. Satellite images show Eritrean troops and artillery across the border. Eye-witness accounts put Eritrean troops on the battlefield.

As one US Official put it - The Eritreans are in Tigray - but they aren't saying it publicly. A senior diplomat believes thousands of Eritreans have been deployed to the region.

A former Eritrean defence minister claimed that his country has deployed four mechanised divisions, seven infantry divisions, and a commando brigade in Tigray. But the Eritrean soldiers are proving to be an unruly lot. On Sunday - they accosted a United Nations team in Tigray.

The UN officials were fired at, and detained. But Ethiopian authorities defended the soldiers, pinning the blame on the UN officials.

Also read: Fighting flares in Ethiopia's Tigray as army says closing in on rebellious force

Eritrea's involvement puts the international community in a tight spot because Ethiopia is a key ally of the west, and remains crucial to maintaining peace in the horn of Africa. On the other hand, the Eritrean regime is infamous for human rights violations.

So while the global community has tolerated the operations in Tigray, Eritrean involvement could prove to be a red line.