The expression “no justice, no peace” is usually associated these days with US demonstrations against police killings of African-Americans. But it also applies to Syria, according to Stephen Rapp, who has just stepped down as US ambassador-at-large and chief of the State Department’s Office of Global Criminal Justice.

In his first interview since leaving office Aug. 7, Rapp told Al-Monitor that any diplomatic effort to end the civil war in Syria would fail unless accompanied by a process of transitional justice that targets the worst offenders, including Syrian President Bashar al-Assad.

“You can’t even get to peace unless a justice process is developed that’s going to give people confidence that the authors of mass rape and killing are going to be held to account,” Rapp said in the Aug. 11 interview. “Anything else won’t last.”

In the job for six years, Rapp said that “a great deal has been accomplished” in collecting and organizing evidence of crimes in Syria, even though no officials have been prosecuted so far. He pointed to the work of a UN commission whose mandate has repeatedly been renewed, the creation with US support of the Syrian Justice and Accountability Center and work by grantees of that body including the Commission on International Justice and Accountability.