KAMPALA, Uganda (AP) — Ethiopia's federal troops for almost a week have been battling troops loyal to the Tigray regional government, raising fears of civil war in Africa's second most populous country. Just a year ago, Ethiopian Prime Minister Abiy Ahmed was receiving the Nobel Peace Prize for his dramatic political reforms. What happened? Here’s a timeline of recent events:

APRIL 2018: A NEW PRIME MINISTER

The Tigray People's Liberation Front had dominated Ethiopia's governing coalition of ethnic-based groups during the long rule of authoritarian Meles Zenawi, who died in 2012. But under growing pressure from months of anti-government protests demanding greater freedoms, Prime Minister Hailemariam Desalegn stepped aside and the ruling coalition named the little-known Abiy as prime minister for a fresh start. The youthful former intelligence operative quickly made waves, announcing that “this is high time for us to learn from our past mistakes and make up for all the wrongs done in the past.” Reforms quickly followed as his government released political prisoners, welcomed home exiled opposition figures and vowed to open the political space and hold free and fair elections. Abiy also shocked the region by making peace with neighboring Eritrea after a border war, and promoting similar efforts in the wider Horn of Africa.

OCTOBER 2019: A NOBEL PEACE PRIZE

The following year, Abiy was awarded the Nobel Peace Prize for his sweeping reforms. “No doubt some people will think this year’s prize is being awarded too early,” the Nobel committee said. But “it is now that Abiy Ahmed’s efforts deserve recognition and need encouragement.” Abiy — of mixed ethnic heritage and the son of a Muslim and an Orthodox Christian — was seen as a symbol of what he would like to achieve in a country of some 80 ethnicities and 110 million people. But experts warned that the fractious mix could also bring him down. Already, trouble had been brewing. A thwarted attempt to hurl a grenade at Abiy led to a deadly explosion at a massive rally in the capital, Addis Ababa. And Ethiopia’s military chief was shot dead by his bodyguard amid a failed coup attempt against the Amhara regional government, leading Abiy to address the nation wearing military fatigues.

JULY 2020: GROWING ETHNIC VIOLENCE

Hundreds of people were killed and thousands arrested during days of unrest following the shooting death of a popular singer. Hachalu Hundessa had been a rallying voice in the anti-government protests that preceded Abiy's rise to power. Abiy told the nation that the dissidents to whom he had extended an offer of peace had “taken up arms” in revolt against the government, and hinted at connections to the grenade attack and attempted coup. The military was deployed during the outrage that followed the singer's death, and authorities cut off internet service for weeks, leading human rights groups to again warn of the return of repressive government measures.

SEPTEMBER 2020: TIGRAY TENSIONS SPIKE

The well-armed TPLF in the Tigray region had been feeling increasingly marginalized and targeted by Abiy's reforms, and when he moved to transform the country's ruling coalition into a single Prosperity Party, the TPFL opted out. The TPLF also objected to the delay of Ethiopia's national election, blamed on the COVID-19 pandemic, and the extension of Abiy's stay in office. The Tigray region defied the federal government by holding a local election, leading to the current situation where each government now regards the other as illegal. Tigray officials had warned that an intervention by the federal government would amount to a “declaration of war," but Abiy ruled out a military intervention. He said, however, that "if the party doesn’t take part in the general election, it won’t be acceptable." The federal government then further angered the TPLF by moving to divert funding to local administrations in Tigray instead of the regional government.

NOVEMBER 2020: THE BRINK OF CIVIL WAR

As America wrapped up its Election Day, Abiy in the early morning hours of Nov. 4 announced that he had ordered the military to confront the well-armed Tigray regional government, accusing it of a deadly attack on a military base and declaring “the last red line has been crossed” after months of alleged provocations. Internet and phone lines were cut in the Tigray region, where a statement on Tigray TV accused the federal government of deploying troops to “cow the people of Tigray into submission by force.” There has been no sign of Abiy's government acting on calls by the international community for dialogue, with some experts warning that talks had little chance if the federal government sees the TPLF as illegal. What Abiy seeks to describe as a “law enforcement action” against what he regards as an illegal TPFL “clique" continues, with hundreds of people reportedly killed. Experts worry what would happen if the conflict inspires other parts of Ethiopia that have sought more autonomy.