Even as an international court tries Bosco Ntaganda for alleged war crimes, other ex-rebels hold key posts in the Democratic Republic of Congo, from President Joseph Kabila to government ministers, senators and generals.

Since September 2, the former militia chief has been on trial at the International Criminal Court (ICC) in The Hague for war crimes and crimes against humanity committed in 2002-2003 in the turbulent northeast of the country.

Nicknamed "the Terminator" because of a pitiless reputation, Ntaganda took part in successive uprisings before he was made an army general in 2009 under an amnesty given to several armed groups. For Kinshasa, such was the price to pay for peace.

Military integration for former foes became a recipe for easing tensions in the wake of the Second Congo War (1998-2003), when foreign armies and Congolese rebels battled the regime of ex-rebel Laurent-Desire Kabila, who ousted longtime dictator Mobutu Sese Seko in 1997.

After Kabila was assassinated at his palace by a bodyguard in 2001, he was swiftly replaced at the top by his son Joseph, an officer in the Alliance of Democratic Forces for Liberation (AFDL) onetime rebel movement.

The Second Congo War was followed by a transitional period, monitored by a large United Nations mission deployed in the vast central African nation.

From 2003, Kabila shared power with four vice-presidents, two of whom came from rebel ranks: Azarias Ruberwa of the Congolese Rally for Democracy (RCD) and Jean-Pierre Bemba, the wealthy businessman leader of the Movement for the Liberation of the Congo (MLC).

- 'Sorry for those who suffered' -

Defeated by Kabila in a 2006 presidential poll regarded as the first free election in the former Zaire since independence from Belgium in 1960, Bemba is currently also on trial at the ICC in The Hague.

The ex-rebel has retained his elected post as a senator despite war crimes charges arising from atrocities blamed on MLC troops Bemba sent to the neighbouring Central African Republic in 2001 to help put down a coup attempt.

Of around 40 ministers in today's government, a quarter come from the MLC and the RCD, which long since became political parties. The number of army generals and other senior officers from RCD ranks is all but countless.

"Contestation has always been positive," says Tryphon Kin Kiey, minister for relations with parliament and former RCD communications chief. "It makes change possible. If France is where it is today, it's because there have been challenges."

Taking up arms "was useful", says Olivier Kamitatu, former minister of planning from the MLC. Yet "armed rebellion never bears the mark of honour... I feel sorry for those who suffered from it."

For Kamitatu, "the only springboard" to positions of responsibility "remains the people", the politician adds. He is one of a small group whose members just left the presidential majority and urge Kabila to resist the lure of extended power and stand down in 2016, in line with the constitution.

In 2010, the United Nations published a voluminous report giving details of 617 serious crimes that led to the deaths of tens of thousands of civilians between 1993, when ethnic strife erupted in the east of the country, and 2003, the end of the war.

- 'Gulf of impunity' -

Virtually all these crimes have gone unpunished, while eastern provinces, notably North and South Kivu, are roamed by many militias and rebel groups whose activities have displaced hundreds of thousands of villagers.

"There remains a wide gulf of impunity for serious violations of human rights" committed by all parties to conflict, says Jose Maria Aranaz, head of the UN Joint Human Rights Office in Kinshasa.

Once taken into the army, Ntaganda benefitted for several years from protection by the authorities, who refused to give in to pressing calls for the ex-rebel to be turned over to the ICC.

When he felt that the regime was weakening, Ntaganda deserted in 2012 to fight for months with the March 23 Movement (M23), the latest incarnation of mainly ethnic Tutsi rebellion in the east, until it was crushed in late 2013 by the Congolese army and UN troops.

After military reform by law in 2011, Kinshasa refused to give an amnesty to the armed movements in the east and take members into the army.

Amnesties provide no "guarantee of repeat offences" when "there can never be any going back", says Francois Muamba, an ex-MLC member given oversight of the November 2013 peace accord with M23.

Some rebel leaders who tried to negotiate wound up either dead or in prison, but others have gone untouched.

Sheka Ntabo Ntaberi, whose militia is accused of mass rapes, stood in the parliamentary poll of 2011. Unelected, he operates in the bush.