Juba, South Sudan - The future of South Sudan has been thrown into limbo, as the expected return of South Sudan's rebel leader Riek Machar has been repeatedly delayed.



Machar was due to return to Juba on Monday to be sworn in as the first Vice President of South Sudan.



Since December 2013, South Sudan has been engulfed in a bloody civil war that has killed at least 50,000 and displaced 2.3 million people.

A peace deal signed in August between President Salvia Kiir and Machar laid the framework for peace, but it has yet to be implemented.



Machar's return is widely seen as essential to forming a unity government, an important step in ending the country's civil war.



"The return of Machar is a significant moment for the future of South Sudan ... The Transitional Government of National Unity provides the opportunity to unite and stabilise the country," a Western diplomat in South Sudan told Al Jazeera on the condition of anonymity because of the sensitivity around the subject.

Dispute over troop numbers

Machar's arrival in Juba has been delayed because of a disagreement over the number of opposition troops travelling with Machar and his chief of staff, Simon Gatwech Dual, who is under United States and United Nations sanctions.



The opposition has demanded that Dual return to Juba along with the return of Machar.



It was proposed that Dual be flown from Gambela, Ethiopia, by an Ethiopian Airlines flight that was funded by the US government, according to Ezekiel Lol Gatkuoth, head of foreign affairs for the SPLA-IO, the opposition faction of the Sudan People's Liberation Movement.

Because the US cannot fund an individual under its own and UN sanctions, that plan was scrapped, Gatkuoth and other sources told Al Jazeera.



The UN mission in South Sudan (UNMISS) was then supposed to fly Dual along with 45 troops to Juba on Saturday, April 16, according to Gatkuoth.



"He was ready to be flown with two helicopters to Juba, one was taking 23 [troops] and the other 22 [troops]. All of a sudden they were saying the flights were not available until April 20," Gatkuoth said over the phone from Gambela, Ethiopia.



"There is no such plan with UN aircraft," said Ariane Quentier, spokeswoman for UNMISS in an email.



The opposition says that it found a "good samaritan" to charter a plane for Dual on Monday, before the expected arrival of Machar.

Q&A: The future peace in South Sudan

Dual was supposed to fly to Juba with 45 troops, and Machar was scheduled to arrive later with 162 troops, as part of his presidential guard, according to Gatkuoth.



None of the planes arrived on Monday, and the county has been thrust into a political waiting game.

South Sudanese Minister of Information and Broadcasting Michael Makuei Lueth said on Tuesday that Dual's plane did not get clearance to land because it did not go through the proper channel. He said that Dual could only arrive with 40 troops, and Machar cannot travel with any troops.



Machar’s protection force "is already on the ground with all of their armaments. He does not need any additional armed forces or arms in Juba," Lueth said in a statement to journalists on Tuesday.



Both parties agreed to have 1,410 troops located in Juba, Lueth said, and there are already 1,370 opposition soldiers in the capital.



Lueth said that a joint military committee between the rebels and opposition, known as JMCC, must approve the armament of the 40 troops, and be verified by a group of international monitors, CTSAMM.



As of Tuesday night, the resolution of the disagreement over the number of troops travelling with Dual and Machar is unknown, but a spokesperson for Machar said he "will be arriving [In Juba] on April 20 if all goes well".