Leader of the Sudan People's Liberation Movement in Opposition (SPLM-IO) Riek Machar shakes hands with South Sudan's President Salva Kiir after a tripartite summit at the State House in Entebbe, Uganda, Nov. 7, 2019.
Leader of the Sudan People's Liberation Movement in Opposition (SPLM-IO) Riek Machar shakes hands with South Sudan's President Salva Kiir after a tripartite summit at the State House in Entebbe, Uganda, Nov. 7, 2019.

The United States says it will "re-evaluate" its relationship with South Sudan after the country's leaders failed to form a transitional unity government by Tuesday's deadline.

The U.S. State Department said Wednesday it is "gravely disappointed" by the failure of South Sudanese President Salva Kiir and opposition leader Riek Machar to meet the November 12 deadline, which the sides agreed to earlier this year.

"Their inability to achieve this basic demonstration of political will for the people of South Sudan calls into question their suitability to continue to lead the nation's peace process," said the statement from spokesperson Morgan Ortagus.

Secretary of State Mike Pompeo released a similar statement on Twitter.

South Sudan is trying to emerge from a five-year civil war that killed tens of thousands and at its height displaced more than 4 million people.

Kiir's government and various rebel groups signed a peace agreement in August 2018 that required the sides to form a unified national army and create a transitional government. But implementation has been stalled, in part by a failure to agree on the country's internal political boundaries.

President Kiir angered opponents in 2015 when he divided South Sudan into 28 states, up from the previous 10.

The State Department said the U.S. will work "bilaterally and with the international community to take action against all those impeding South Sudan's peace process."