The top monitor of South Sudan's peace deal said he and diplomats support the disputed appointment of a new vice president in order to support the country's shaky peace agreement.

Although the legitimacy of Taban Deng as First Vice President is questionable, diplomats will work with him because they "don't have an option," said the chairman of the Joint Monitoring and Evaluation Commission, former Botswana President Festus Mogae, in an interview with The Associated Press on Sunday.

Deng was appointed last month by President Salva Kiir after he controversially dismissed opposition leader Riek Machar from the vice president position.

Machar and his rebel forces fled the capital last month after fighting in Juba killed hundreds of people. Machar fled the country last week and is currently in Khartoum, Sudan.

Mogae's acceptance of Deng has apparently been endorsed by the United States. Last Monday, U.S. Secretary of State John Kerry said Deng's appointment was legal and State Department officials said their goal is to avoid further military action.

Mogae said neither Kiir's government nor Machar want the peace agreement.

"There is no political will to implement the agreement. They are bent on a military solution, not a political solution," Mogae said. "I am more disillusioned or less optimistic than I was when I first came. I thought that common sense and logic could persuade them to do the right thing."

Mogae said negotiations are continuing to negotiate with Machar's SPLM-IO party but added that "potentially you have two SPLM-IO: one which will enter negotiations, and another in the bush and fighting,"

South Sudan gained independence in 2011, but it was rocked by a civil war that began in December 2013 and lasted until the peace agreement was signed in August 2015. At least 50,000 people were killed, and more than 2 million were displaced.