The US military is developing alternatives for evacuating the US Embassy in Sudan, Defense Secretary Lloyd Austin said on Friday, as the Biden administration considered withdrawing staff from the country’s increasingly volatile capital.

“We’ve sent some forces into the theater to make sure we have as many options as possible if we’re called upon to do something.” “And we haven’t been called on to do anything yet,” Austin said at a news briefing at Germany’s Ramstein Air Base. “No decision on anything has been made.”

Two U.S. officials said a decision on a possible evacuation of the embassy is expected soon, but it was unclear if there will be a public announcement.

Forces commanded by two previously allied leaders of Sudan’s ruling council began a violent power struggle last weekend. Hundreds have died so far and a nation reliant on food aid has been tipped into what the United Nations calls a humanitarian catastrophe.

U.S. Army General Mark Milley, chairman of the Joint Chiefs of Staff, discussed the safety of Americans in Sudan during a phone call on Friday with Sudan’s army chief, General Abdel Fattah al-Burhan, his office said.

John Kirby, the White House national security spokesperson, said President Joe Biden approved a plan this week to move U.S. forces nearby in case they are needed to help evacuate American diplomats, without saying where. Reuters has previously reported their repositioning to Djibouti.

“We are simply pre-positioning some additional capabilities nearby in case that they’re needed,” Kirby told reporters.

With the airport in Khartoum caught in the fighting and the skies unsafe, nations including the United States, Japan, South Korea, Germany and Spain have been unable to evacuate embassy staff.

A Western diplomat said the evacuation situation in Sudan is one of the most difficult they have seen, with Americans likely focused on getting a ceasefire and using that to get personnel out.

“In this case, the civil war starts in the capital, fighting is exactly where the embassies are and where the airport is. It’s unusually difficult,” the diplomat said.

Cameron Hudson, a U.S. Africa policy expert at the Center for Strategic and International Studies and former director for African affairs at the National Security Council, said the level of violence in Khartoum makes the situation for evacuation unpredictable.

“The major challenge is there’s a war going on across all corners of the city and the international airport in the middle of the city is not functional right now, so the challenge is moving people to a safe space to evacuate them,” Hudson said.

Washington has said private American citizens in Sudan should have no expectation of a U.S. government-coordinated evacuation. State Department deputy spokesperson Vedant Patel said the United States was in touch with several hundred American citizens understood to be in Sudan.

Earlier on Friday, the State Department confirmed the death of one U.S. citizen in the country.