Policy analyst Henry-Pacifique Mayala told the BBC that Kabila had been left with few options for regaining political influence.
“He actually was left with no other choice,” he said.
Facing a death sentence after being convicted in absentia of treason, as well as US sanctions over his alleged support for the M23, Kabila may have sought assurances that the partnership could serve his interests, Mayala suggested.
“I’m not sure that he is making this huge leap in the dark without having received considerable assurance,” Mayala said, adding that the M23’s military strength could give Kabila greater leverage in any future negotiations with the Congolese government.
Kabila’s involvement also raises questions about whether the conflict could spread beyond the east.
The M23’s territorial gains have been concentrated in the country’s eastern provinces, some 1,500km (1,000 miles) from the capital, Kinshasa.
Kabila’s political networks could give the rebellion a broader reach, but that does not necessarily mean it has the capacity to extend its military campaign across the country.
And it is not clear how far Kabila’s national reach extends.
While he was in power, after being named following the mysterious assassination of his father Laurent in 2001, he was often seen as something of an outsider in Kinshasa. He was far more at home speaking Swahili, the lingua franca of eastern DR Congo, as well as east Africa, rather than the Lingala spoken in Kinshasa.
His father’s rebel group actually walked across the country to Kinshasa, also starting in the east, over a period of seven months, before eventually seizing power in May 1996 and ousting long-time ruler Mobutu Sese Seko, who had governed the country as his own personal property for more than 30 years.
There is little suggestion that Joseph Kabila’s FRN would try to repeat that feat but earlier this week, he likened Tshisekedi to Mobutu.
“You have a tyrant who wants to impose and dictate what he thinks is right and not necessarily follow the constitution, which is the supreme law of the land,” he told Conspiracy Trackers Great Lakes (CTGL), a research group which campaigns against disinformation in that part of Africa.