The Central African Republic's northern neighbor, Chad, is a military heavyweight in the region. Under the leadership of President Idriss Deby Itno, it is a driving force behind key decisions in the current crisis. For example, on the question of the president: CAR's interim president Michel Djotodia was invited to attend a summit of the Economic Community of Central African States (ECCAS) in the Chadian capital N'Djamena in January 2014. He then resigned following pressure put on him by President Deby. This was not the first time Chad had decided on the rise and fall of a Central African president. Deby has always considered CAR to be Chad's backyard, says Helga Dickow, an expert on Central Africa at the Arnold Bergstresser Institute at Freiburg University. In the 1990s, former president Ange-Felix Patasse came to power with Chadian support, she said in an interview with DW. "And Djotodia's predecessor, Bozize, was basically only head of government with Deby's approval."

The Chadian president Idriss Deby Itno has been in power for 23 years.

Military might

Chad also has a very strong military presence in CAR. A large part of the 5,500- strong military mission of the African Union (MISCA) was provided by Chad. In December 2013, the intervention force was tasked with bringing stability to the country. In addition to MISCA, there are also some 1,600 French soldiers in the Central African Republic

The alliance between the Chadian and French armies is not new. Chad had already shown itself to be an experienced and important ally during the French intervention in Mali. Since that joint operation, France has now "sided with Deby," says Dickow. "France is now basically supporting a dictator who was previously not socially acceptable. He is now back in the fold of international politics."

However, in the Central African Republic, the population took a skeptical view of the foreign troops. There have been accusations that Chad "supported Seleka rebels and even trained some of them," Dickow told DW.

Chad and Central African Republic share a long border

"The Chadian troops in CAR have reached a size that is uncontrollable,” says Acheikh Ibn-Oumar, a Chadian opposition politician and former ambassador to the United Nations.

"Chadian troops have been crossing the almost one thousand kilometer-long (620 miles) border with CAR, saying they are trying to control it," he told DW.

Brice Kevin Kapayen, a human rights activist and member of the CAR transitional parliament, confirmed that Seleka supporters had entered CAR. "They are armed. The question is: who gave them arms?" The spokesman of the Chadian government has denied any involvement. "But he is not here. He is not in Bangui to see what is happening. We have evidence for everything we are saying," said Kapayen.

Chad is currently a non-permanent member of the UN Security Council. In negotiations, Chad argued against sending a UN peacekeeping mission to the Central African Republic. "They want to find an African solution," says Helga Dickow.

Behind this handshake between Chad's President Deby (right) and Michel Djotodia, pressure was being exerted

The oil factor

Chad has built up its military strength thanks to its oil revenue, says Dickow, and this makes the country appear stable and powerful. However this appearance is deceptive. President Deby is looking for a way to secure the southern borders. He wants to make himself militarily impregnable as he did before in the Darfur conflict when rebels from Sudan threatened his hold on power. "The other crisis region which could be a gathering point for rebels who could rise up against N'Djamena is the border region between CAR and southern Chad," Dickow said.

She sees another reason why this border is of interest for Deby. In southern Chad and in the north of the Central African Republic are oil wells. "Any trouble in this border region would also jeopardize oil production in Chad."