South Sudanese rebel leader Riek Machar arrived in the capital Juba on Tuesday after repeated delays to implement a peace agreement due to end his 28-month military conflict with President Salva Kiir, which has killed tens of thousands of people.
Machar touched down at Juba airport in a UN plane, according to journalists at the airport.
Flying in from Gambella in Ethiopia, Machar was expected to immediately be sworn in as vice president and then to address a rally.
Machar's swearing-in was due to open the way for the inauguration of a transitional unity government, which will draft a new constitution.
"I hope that with my return, those remaining obstacles will be resolved. ... I want peace to prevail," Machar told reporters on arrival.
The rebel leader had already been expected to land a week ago, but his arrival was delayed by disagreements about the number of troops and weapons that would accompany him.
He was preceded by the rebels’ top commander Simon Gatwech Dual, who arrived in Juba on Monday. The rebels said he was accompanied by nearly 200 troops who would provide security for Machar.
The troops, who brought 20 machine guns and 20 rocket launchers, were due to join more than 1,300 rebel troops who had arrived in Juba earlier as part of the peace deal.
Machar had fled the capital in December 2013 when a power struggle pitting him against Kiir turned violent.
He was recently staying in Ethiopia, from where he travelled to the South Sudanese border town of Pagak in order to return to Juba. He then went to Gambella to take the plane from there.
Machar already served as Kiir's vice president once before, after South Sudan gained independence from Sudan in 2011, until Kiir sacked him in 2013.
The conflict has displaced more than 2 million people, while more than 5 million face food insecurity, according to the United Nations.
The conflict has also been marked by widespread atrocities and it has ignited ethnic hatred.
Kiir and Machar had signed the peace agreement in August, but it did not entirely stop the fighting and its implementation was delayed.
The UN and the United States had mounted pressure on Machar to return to Juba without delay.
“The scope of future US engagement in helping South Sudan confront the country's security, economic and development challenges ... will depend on the parties demonstrating commitment to work together to implement the agreement,” the US State Department said in a statement.