Ethiopia’s Nobel Peace Prize winner says he will lead his country’s army “from the battlefront” beginning Tuesday, a dramatic new step in a year-long war.

“This is a time when martyrdom is required to lead a country,” Prime Minister Abiy Ahmed said in a statement posted on social media Monday night. With rival Tigray forces approaching Addis Abeba, his government declared a state of emergency earlier this month.

Tens of thousands of people are thought to have died in the war between Ethiopian and allied forces and fighters from the country’s northern Tigray region, which had long dominated the national government before Abiy took office. The United States and others have warned that the Horn of Africa’s second-most populous country could fracture and destabilize.

An official told News reporters on Monday that the US military was closely monitoring the situation in Ethiopia while “conducting prudent planning,” but there has been no indication that American forces are preparing for a mass evacuation similar to what happened in Kabul following the Taliban’s takeover of Afghanistan.

The State Department, on the other hand, has made it abundantly clear that any American citizens still in Ethiopia — and it’s unclear how many there are — should leave immediately. “Our core message is: Don’t wait until things get worse before making a decision to leave,” a senior State Department official said during a briefing on Monday.

“Leave before things change,” the official advised, adding that the US Embassy in Addis Abeba was “unlikely to be able to assist” US citizens fleeing if commercial travel options “become unavailable.” According to the officials who gave the briefing in Washington, the message appeared to be getting out. People were reportedly showing up at the embassy seeking advice.

In response, Getachew Reda, a spokesman for the Tigray forces, tweeted that “our forces will not relent on their inexorable advance towards breaking (Abiy’s) chokehold on our people.” The Tigray forces say they are putting pressure on Ethiopia’s government to lift a months-long blockade of the Tigray region, which has a population of 6 million people, but they also want Abiy out of power.

The prime minister’s statement also claimed that the West is attempting to defeat Ethiopia, the latest retaliation for what his government has described as international meddling. Envoys from the African Union and the United States have maintained diplomatic efforts in pursuit of a cease-fire and talks on a political solution without preconditions.

A senior State Department official told reporters shortly after Abiy’s announcement that the US still believes “a small window of opportunity exists” in the mediation efforts.

In a year, Abiy’s government has shifted from calling the Tigray conflict a “law enforcement operation” to calling it a “existential war.” With Ethiopia’s military reportedly weakened in recent months, and its withdrawal from Tigray in June, ethnic-based regional forces have stepped up, and Abiy’s government has called on all able citizens to join the fight. Awol Allo, a senior lecturer in law at Keele University in the United Kingdom, was taken aback by Abiy’s announcement. “The announcement is replete with martyrdom and sacrifice languages,” he tweeted. “The fact that this is so extraordinary and unprecedented demonstrates how desperate the situation is.”

In his Nobel acceptance speech for 2019, the Prime Minister spoke passionately about war: “Years ago, I crawled my way to peace through the dusty trenches of war… I saw the ugliness of war firsthand in frontline battles… War is the pinnacle of hell for everyone involved. I’m aware because I’ve been there and back.”

Abiy received the Nobel Peace Prize for bringing peace to neighboring Eritrea, on whose border he fought while stationed in the Tigray region.

The terms of that peace agreement were never made public. Critics of the current conflict claim that the agreement was instead a deal for the two countries to wage war on the Tigray leaders, who were unpopular among many Ethiopians for their repressive 27-year rule despite significant development gains.

Eritrean soldiers have been blamed for some of the war’s most heinous atrocities, despite Abiy’s denial for months that they were inside Tigray.