Khmer Rouge leaders are currently on trial by the UN-backed tribunal for genocide. The tribunal is facing serious roadblocks, including Tuesday resignation of UN judge Mark Harmon. Judge Harmon's resignation, said to be made for personal reason, coincides with Cambodia's failed arrest of two key suspects he named for the indictment in the ongoing trial. VOA Khmer's Sok Khemara talked to Stephen Rapp, US Ambassador-at-large of War Crimes, and has the interview.