The United States on Monday welcomed the start of the trial of former Chadian dictator Hissene Habre, hailing "an important step toward justice" for those who suffered under his iron-fisted rule.
State Department spokesman John Kirby said Washington "commends the government of Senegal and the African Union" for bringing Habre to trial in Dakar after a 19-month investigation.
"This trial is an important step toward justice for the victims of atrocities committed under Habre's rule from 1982 to 1990," Kirby said in a statement.
It should also "serve as yet another warning that, no matter their position, perpetrators of atrocities will be held accountable."
Under a previous US administration of then president Ronald Reagan, Washington had backed Habre, now 72, as a bulwark against Libya's Moamer Kadhafi.
But Human Rights Watch has acknowledged that the Obama administration has been one of the strongest supporters of bringing Habre to justice.
In a show of US support, US ambassador to Senegal, James Zumwalt, and ambassador-at-large for war crimes, Steven Rapp, were both in the courtroom to witness the start of the hearing.
The United States "supports a fair and impartial trial, and is committed to helping end impunity for the worst crimes known to humanity," Kirby added.
Habre is on trial for crimes against humanity, war crimes and torture in Chad from 1982 to 1990.
Rights groups say 40,000 Chadians were killed under a regime propped up by crackdowns on opponents and the targeting of rival ethnic groups Habre perceived as a threat to his grip on the Sahel nation.
Habre was overthrown by rebel troops in December 1990 and fled to Senegal, where he was arrested in June 1993.