WASHINGTON (Reuters) - The United States has recalled its ambassador from South Sudan after the leaders of formerly warring factions failed to agree on a unity government, the U.S. State Department said on Monday.

Ambassador Thomas Hushek will return for consultations “as part of the re-evaluation of the U.S. relationship with the Government of South Sudan given the latest developments,” the department said in a statement.

Secretary of State Mike Pompeo tweeted that Washington would “work with the region to support efforts to achieve peace and a successful political transition in South Sudan.”

South Sudan’s ministry of foreign affairs said it was still engaging with the United States.

“Our position is still the same. We are still engaging with them and we have a good relationship,” spokesman Mawien Makol told Reuters.

He said differences over the extension of time to form a unity government “should not break our relations. The extension is meant to fully implement the peace agreement.”

After a devastating five-year civil war, South Sudanese President Salva Kiir and opposition leader Riek Machar signed a peace deal in September 2018, under pressure from the United Nations, the United States and regional governments.

On Nov. 7, they agreed to give themselves 100 days more beyond a Nov. 12 deadline to form the unity government, and Washington said it was “gravely disappointed”.

The conflict began after Kiir sacked Machar as vice president. It killed an estimated 400,000 people, triggered a famine and created Africa’s biggest refugee crisis since the 1994 genocide in Rwanda.