JOHANNESBURG (AP) — The U.S. has called its ambassador to South Sudan back to Washington for consultations as Washington reevaluates its relationship with the country after a delay in implementing a fragile peace deal.

The unusual public U.S. State Department statement was echoed in a tweet Monday by Secretary of State Mike Pompeo as the U.S. signals its frustration with the failure of South Sudan’s rivals to meet this month’s deadline to form a coalition government.

South Sudan President Salva Kiir and opposition leader Riek Machar agreed to postpone that key step for 100 days. They had faced a Nov. 12 deadline but said security and governance issues needed to be resolved.

The U.S. said the delay “calls into question their suitability to continue to lead the nation’s peace process.”