The American war crimes ambassador said Thursday the U.S. is committed to ending impunity for crimes against humanity, in a speech signaling a softening of hostility toward the International Criminal Court.
Stephen Rapp's brief remarks marked the first time a U.S. diplomat has addressed the 110-nation Assembly of State Parties, which oversees the court's work and budget.
He also held a string of bilateral meetings and told delegates he was there to listen and learn.
Rapp underscored Washington's history of helping prosecute those responsible for atrocities dating back at least to the Nazi war crimes trials in Nuremberg.
The world's first international war crimes tribunal began work in 2002. It is a court of last resort to prosecute people suspected of committing war crimes in its member states, if those countries cannot or will not conduct the trials themselves.
The U.N. Security Council also can ask the court to investigate a case.
The United States refused to ratify the court's founding treaty, the 1998 Rome Statute, partly because of fears the court could become a forum for politically motivated prosecutions of troops in unpopular wars like Iraq.
But the U.S. has "not been silent in the face of crimes against the basic code of humanity," Rapp said. "Far from it: We have worked shoulder to shoulder with other states to support accountability and end impunity for hauntingly brutal crimes in the former Yugoslavia, Rwanda and elsewhere."
The U.S. allowed the Security Council to call on the court to intervene in the Sudanese region of Darfur, clearing the way for it to issue an arrest warrant last March for Sudanese President Omar al-Bashir.
Rapp also signaled that Washington wants a role in drafting a definition of the crime of aggression for inclusion in the court's statutes.
Diplomats and lawyers have been haggling for years over a definition of aggression, and a way of referring those responsible it to the court. The debate is expected to come to a head next year at a conference in Uganda to discuss changes to the Rome Statute.
Rapp said the decision to prosecute a crime of aggression should rest with the Security Council _ where the U.S. has a veto, as do Britain, France, Russia and China.
Other countries argue the U.N. General Assembly or the International Court of Justice should have that power.
Rapp is a strong advocate of international criminal justice who has served as a prosecutor at the U.N. Rwanda tribunal and as chief prosecutor at the Special Court for Sierra Leone.
His appointment earlier this year as President Barack Obama's roving war crimes ambassador was welcomed by advocates of closer engagement between Washington and the International Criminal Court.
"We very much welcome their presence," Elizabeth Evenson of New York-based Human Rights Watch said of Rapp and his team. But she acknowledged that American ratification of the court was likely still years away.