Secretary-General Antonio Guterres appointed veteran South African diplomat Nicholas Haysom on Friday to head the U.N. peacekeeping mission in South Sudan.

Haysom, who is currently the secretary-general's special adviser for Southern Africa, previously served as head of the U.N. political mission in Afghanistan and as special envoy for Sudan and South Sudan.

In 2018, he was appointed to head the U.N. mission in Somalia but was expelled by the government on Jan. 1, 2019, after questioning the arrest of a political candidate with an extremist history.

U.N. spokesman Stephane Dujarric announced Haysom's appointment to replace David Shearer of New Zealand. He said Gecretary-General Guterres is grateful to Shearer "for his exemplary leadership of the UN Mission during the time of critical developments and challenges for South Sudan."

Ten years after South Sudan gained its independence from Sudan and two years after its own deadly civil war ended, large-scale fighting has subsided but clashes continue between communities and between the government and groups that did not sign a peace deal.

The almost 20,000-strong U.N. peacekeeping mission Haysom will head has a primary mandate to protect civilians and help build peace.